Stretching over 15 miles, Norway's Lærdal Tunnel has been the longest road tunnel in the world since it was built in the 1990s. 

Now, the country will construct the world's first tunnel for ships — which will get between 70 and 120 vessels per day.

As noted by BBC News, the tunnel started gaining public support in the 1980s, and the Norwegian Coastal Administration (NCA) has since embarked on several feasibility studies to see how it could come to fruition.

In March, Terje Andreassen, the tunnel's project manager, told Business Insider that the NCA submitted its findings to Norway's Department of Transport. The project got official approval in April. It will be financed by the Norwegian Parliament, which has already designated approximately $117 million ($1 billion NOK) for the NCA's research.

Construction will likely start in 2019, and the tunnel is expected to open in 2023, Andreassen told the AP.

The NCA worked with Snøhetta, an Oslo-based architecture firm, to create renderings of what the tunnel will look like. Check them out below.

SEE ALSO: The 14 most expensive skyscrapers built in the last 20 years

Norway's Stad Ship Tunnel will be located on the Stadhavet Sea, an area known for heavy winds and hurricanes.

Stormy weather makes it almost impossible for ships to travel in the area. Vessels often wait for hours or even days before it becomes safe enough to cross, Andreassen says. His team at the NCA conducted research on the feasibility of building the tunnel.

The Stad Tunnel will allow for safer passage along the sea, Andreassen says. Here's a rendering of what it will look like:

Warning: Minor spoilers ahead for "Game of Thrones" season 7.

HBO is rolling out more teasers for "Game of Thrones" season seven, though none of them has shown footage from upcoming episodes.

The latest of these comes from an HBO commercial that stars characters from a variety of shows on the network all saying "ahhhh"in the classic HBO opening tone.

Naturally, the bulk of the "Game of Thrones" cast was included, and most of the characters appear to be dressed in new costumes for season seven.

Keep scrolling for a look at all your favorite "Game of Thrones" characters in their new looks for season seven.

SEE ALSO: All the 'Game of Thrones' deaths, ranked from least tragic to most tragic

First up is Daenerys, all dressed up for winter. Her new structured dress is lined with fur and completed with a cloak fastened by a clasp with a three-headed dragon.

In the latest season seven teaser, we saw Daenerys in Dragonstone, the castle where Stannis Baratheon lived. Her new throne looks pretty awesome, and we can't wait to see her finally in Westeros.

Tyrion is looking fabulous as the Hand of the Queen in a striped top with leather sleeves and that striking silver pin that marks him as the Hand.

Keeping with the new black theme, Missandei has an updated version of the outfit she wore throughout season six.

The INSIDER Summary:

• The World's 50 Best Restaurants is a list that's compiled annually.
• The ranking is based on votes from over 1,000 international leaders in the restaurant industry, including food critics and writers, chefs, and restaurateurs.
• This year, six restaurants in South America made it onto the list.

The annual World's 50 Best Restaurants list was just released.

This year's list includes six restaurants in South America.

Peru dominated, taking up three of those six spots.

Keep scrolling to see the other countries that made it.

6. Tegui, Buenos Aires, Argentina

Click here to learn more about Tegui >

5. Boragó, Santiago, Chile

Click here to learn more about Boragó >

4. Astrid y Gastón, Lima, Peru

Click here to learn more about Astrid y Gastón >

The INSIDER Summary:

• Diners are a beloved part of the American eating experience.
• Here are 11 classic diners that have stood the test of time.

There’s something new and trendy every day in the food world. Today it’s pink pitaya bowls covered in vegan granola and banana slices. Yesterday it was perfectly sliced avocados on house-made bread. Tomorrow it will probably be cricket flour pancakes and spirulina chocolate bars.

In the midst of all that newness, it’s easy to forget about the oldies. But over the years of political, social, and culinary change, one American eating experience has remained the same: the diner. Sure, some places are serving meatless “beef” burgers and Gruyère grilled cheeses, but many are the same greasy spoons as they always were and always will be.

So take a break from all of the trendy stuff, grab some cash, and head to one these 11 iconic American diners that have stood the test of time.

Rainbow Drive-In

At the Rainbow Drive-In in Honolulu, Hawaii, burgers and fries are replaced by fried pork cutlets and macaroni salad, Hawaii-style. It's called a plate lunch and has been the quick-and-easy comfort food of choice on the islands since the 1950s. Locals and tourists alike can attest that few places are more iconic than the flag-adorned Rainbow Drive-In, which has been around since 1961.

Pann's

Conjure up an image of the classic all-American diner, and chances are you're picturing something like Pann's in Los Angeles. From the neon-lettered sign to the faux-futuristic architecture that was oh-so-popular back in the late 1950s (called Googie, if you're curious), the looks of this eatery on La Cienega encompass everything that an old-school diner has to offer. So much so, in fact, that it has made several silver screen cameos. Pann's which has been family-owned and operated since it opened in 1958, serves up a mean all-day breakfast, but the real draw here is the consistently fabulous fried chicken — some say it's the best in Los Angeles. Order it on a waffle, or with a side of creamy mac and cheese.

Original Hotcake House

Few things are better than hitting a good greasy spoon after a night on the town, and in Portland, that greasy spoon is usually the Original Hotcake House. Not to be confused with the International House of Pancakes (God forbid), this institution has been slinging out piles of pancakes and other diner classics 24/7 for over half a century. It's recognizable by its blazing sign and yellow-and-turquoise exterior.

After years of answering question after question about being a twin, I can speak for the masses when I say that twins are a fascinating phenomenon.

It's estimated that only 3% of the population is a twin and with such small odds, it's no wonder why most people are so intrigued by the idea. Every time I've ever told someone that I'm a twin, I am met first with surprise and then intense curiosity — people want to know anything and everything about being a multiple.

So, in effort to help the other twins out there avoid those same endless questions, here is everything you never knew about being a twin.

Twins don't have matching fingerprints or the same DNA.

Despite popular belief, twins are not clones of each other. Twins don't share the same fingerprints for example because even though they share a womb, they sit in different places in the womb, which gives them a different set of prints.

They also don't share the same DNA because studies have found that identical twins can have different DNA sequences.  

While we're on the topic of science, it's also important to remember that boy-girl twins are almost never identical, but fraternal — except in cases of a rare chromosomal defect.

Having twins does not skip a generation.

There's a popular rumor that having twins can skip a generation, but science doesn't back that up at all. It's a complete myth. 

Having twins can, however, be genetic. Having identical twins is not genetic, but having fraternal twins can be. Women who have a set of fraternal twins as siblings are 2.5 times more likely to have twins than an average woman.

And just so you know, when it comes to having twins, only the mother's genes matter. The chances of having twins also goes up with older age and certain pregnancy methods such as in vitro.   

Twins come with a built-in best friend.

Excuse my cheesiness for a moment, but having a twin is like getting assigned a best friend at birth. Sure, there are hundreds of twins who may disagree, but more often than not twins have a special bond that can't be denied.

After all, many twins shared their rooms, their clothes, and their parents' attention, not to mention a womb. It'd be harder to not be friends with them.

Between the 1950s and mid-1990s, tens of thousands of immigrants constructed a towering community 12 stories high across a 6.4-acre lot in Hong Kong.

It was called the Kowloon Walled City.

With a population of 33,000 squeezed into a tiny lot, the city at its peak was 119 times as dense as present-day New York City. Although it faced rampant crime and poor sanitation, the city was impressively self-sustainable until its demolition began in 1993.

In the late '80s, the Canadian photographer Greg Girard found his way into the windowless world.

He shared photos and thoughts about his time in Kowloon Walled City with Business Insider. You can check out the rest, along with essays and work from the photographer Ian Lambot, in "City of Darkness: Revisited."

SEE ALSO: Inside the Australian mining town where 80% of people live underground

Though Hong Kong had been under British rule for decades by the time construction began, a clause in an 1842 treaty meant China still owned the property that would become Kowloon. Caught in legal limbo, it was effectively lawless.

By 1986, the Walled City had caught the attention of the photographer Greg Girard. Girard would spend the next four years in and out of the city, capturing daily life inside its teetering walls.

The Lego-like city was built over decades as residents stacked rooms on top of one another. The end result "looked formidable," Girard told Business Insider, "but who knows?"

A house built on speculation in the Pacific Heights neighborhood of San Francisco is now asking $40 million. That makes it the most expensive house currently for sale in the city, according to Curbed.

Bill Campbell of Marble Management developed the property over the last four years, according to the Wall Street Journal. He demolished a 19th-century clapboard house to make room for this 11,000-square-foot limestone mansion.

Whoever buys the home will be able to count high rollers like Oracle billionaire Larry Ellison and Apple design guru Jony Ive as neighbors. 

Val Steele of Pacific Union International and Tom Biss of Sotheby's International Real Estate share the listing for the home, which has yet to formally hit the market.

SEE ALSO: Live like a Soviet billionaire in this over-the-top Long Island mansion, which is back on the market for $85 million

Since the home was built from the ground up, there are no compromises on style.

It makes the most of its wide view with floor-to-ceiling windows throughout the house.

There's plenty of space for multiple sitting and living rooms.

Residents will soon be able to move into a new luxury condo complex that overlooks Manhattan's famed elevated park, the High Line.

The building was one of the last projects by Zaha Hadid, the world-renowned architect who died at age 65 in early 2016. She was the first woman and Muslim to win a Pritzker Prize, often considered the Nobel Prize of architecture.

Located on Manhattan's far west side, the new complex at 520 West 28th Street will be stunning, with an intricate metal-and-glass facade sculpted piece by piece. Inside, it will include 39 units, the most expensive of which is currently asking $50 million. Approximately 50% of the units are already in contract, according to StreetEasy.

Developer Related Companies broke ground in 2014. Samantha Zola, a spokesperson for the building, told Business Insider that the building will open in June 2017. 

Here's a first look inside two of its model condos, which cost $15 million and $4.9 million, respectively.

SEE ALSO: 11 billion-dollar mega-projects that will transform New York City by 2035

DON'T MISS: The Long Island mansion where the real 'Wolf of Wall Street' once lived and partied can be yours for $3.4 million

Hadid's building is located at 520 West 28th on Manhattan's far west side. The four-bedroom apartment pictured below, which spans 4,500 square feet, is listed for $15 million.

The kitchen features a marble island with edges that swoop down like the building's facade. Hadid worked with the Italian designer Boffi to create it.

Interior designer Jennifer Post chose white and muted furniture with colorful, contemporary artwork for the model apartment.

On April 6, the Trump authorized the first direct American assult on the regime of Syrian President Bashar al-Assad during the country's six-year civil war. The night's events marked one of the first known military actions of President Trump's time in office.

During his run for office, however, Trump faced scrutiny for his lack of military service. He received five draft determents ("four for college, one for bad feet") over the course of the Vietnam War.

But before he became a billionaire real estate developer, reality TV star, or commander-in-chief, Trump was a cadet who attended the New York Military Academy.

Founded in 1889, the private school is spread across 120 acres in rural Cornwall, New York, located 60 miles north of Manhattan. The cost of tuition is $41,210 a year at the school, which ranks No. 128 on a list of the best boarding schools in the US by education resource Niche.

The story goes that Trump's parents shipped their 13-year-old son off to NYMA when he began acting up and it became a problem. Some 50 years later, Trump would tell his biographer that his five years' education there gave him more military training than the military could.

Here's what it's like at NYMA.

SEE ALSO: Photos show how the US missile strike on Syria unfolded

The New York Military Academy opened doors in 1889 with the hopes of preparing cadets for "further education and to be effective leaders and responsible citizens."

Source: New York Military Academy

Charles Jefferson Wright, a Civil War veteran and teacher, founded the school under the belief that a military structure provided the best environment for academic achievement.

Source: New York Military Academy

Through the years, the student body has remained small. Two classroom buildings and three dorms accommodate the 28 students who enrolled in the 2016-17 academic year.

Source: New York Military Academy and Wall Street Journal

The Nissan Rogue is one of the most popular cars in the United States.

The Rogue has posted three years of sales growth since 2014 and was the automaker's top-selling vehicle in the US last year. In fact, on a list of the best-selling cars and trucks in 2016, the Rogue ranks 10th overall.

The Honda CR-V may be the most popular SUV in America, but the Rogue is gaining steam. Nissan sold an all-time record of 40,477 units last December.

I got a chance to take the automaker's second-generation model, the 2017 Nissan Rogue, for a spin — and it was an absolute delight.

The vehicle feels luxurious while still acting as a comfortable, easy-to-drive crossover. Scroll down for a closer look:

SEE ALSO: Subaru's 2017 Forester is still one of the best crossover SUVs you can buy

I will be the first to acknowledge that it's difficult for me to fall in love with a crossover SUV outside Subaru. Considering the Forester was my very first car, I've somewhat succumbed to the mind-set that if you're looking for an affordable crossover, that's the way to go.

You can read more about my love for the 2017 Subaru Forester here.

But there's plenty to be excited about with the 2017 Nissan Rogue, which starts at a base price of $23,820. I took a spin in the SL Premium model that costs $31,310, which I consider reasonable given all of its perks.

For those familiar with the Rogue, the 2017 model comes with a revamped front fascia that includes integrated fog lamps with the bumper. It's a powerful look without being ostentatious.

The Marathon des Sables, a six-day race through the Sahara desert, has a hard-won reputation as "The Toughest Footrace on Earth."

The 32nd edition of the race starts April 9 in Southern Morocco, and runs until April 14. 

I took part in the 31st edition of the race, the longest yet at 159 miles. As one of 973 who crossed the finish line, I can attest that the race is not for the faint-hearted.

The route took in towering sand dunes, airless oueds (dried-up riverbeds), and scrambled jebel (rocky hill) ascents.

The distance typically comes in at almost a marathon a day, with the longest stage a punishing double marathon.

Competitors run or walk through 104-degree plus temperatures, carrying their food for the week. Water is rationed. Salt tablets are essential.

Competitors sleep in bivouac tents, which do little to retain warmth when the temperature drops overnight and offer limited resistance to sandstorms.

It is no surprise then that a lot of competitors don't make it to the finish. There were 18 participants who didn't make it past day one in 2016, according to the provisional results, and nearly 60 more dropped out on day two.

In all, around 130 were forced to drop out, often through no fault of their own. The desert is relentless, and there is a large slice of luck involved in surviving what it has to throw at you.

This is what "The Toughest Footrace on Earth" is like:

The event requires quite a bit of kit. We had to carry at least 2,000 calories a day for seven days, with the bulk of this made up by caloric freeze-dried meals. We also had to pack survival kit with items ranging from a venom pump to a signaling mirror.

We flew in to Ouarzazate in Morocco on Friday, April 8, before boarding coaches for the six-hour drive to the first bivoauc.

The bivouac camp has around 170 tents, each sleeping a maximum of eight competitors. The tents are organized by nationality, with large British and French contingents dominating camp. I stayed with three friends and a British runner named Dave who we met on the bus.

The Trump reflation trade has peaked, according to DoubleLine Capital CEO Jeff Gundlach.

Gundlach held a webcast on Tuesday about his firm's asset allocation strategy, and he broadly updated clients on his thinking about markets.

If the reflation trade is over, returns from investments that were tethered to an expected boost to inflation because of President Donald Trump's economic policies may be muted.

Gundlach sees inflation at 1.85% this year and does not think the 10-year yield will hit 3%.

Gundlach expects, amid high stock valuations, no more than a 5% gain in the S&P 500 unless sales rise.

Thanks as always to DoubleLine Funds for allowing us to run this presentation.

Retailers are closing thousands of stores in one of the biggest waves of closures in years.

But there's one company bucking that trend: Dollar General. 

Instead of shutting down stores, Dollar General is opening hundreds more locations.

The discount chain says it plans to open 1,000 stores this year, bringing its total store count to more than 14,300.

The chain announced its plans after reporting that sales grew nearly 14% in the most recent quarter, to $6.01 billion. 

We went to a Dollar General store in Richmond, Virginia, to find out what makes it so successful.

SEE ALSO: The Target boycott cost more than anyone expected — and the CEO was blindsided

At the entrance of the store, shoppers are greeted with a "last chance" table of discounted goods.

The store feels tiny. Most Dollar General Stores range between 7,000 and 10,000 feet which is about half the size of a CVS store. It's lit with bright, fluorescent lights and features narrow aisles with basic metal shelving.

To the left of the entrance, there's a large selection of snacks, drinks, and candy similar to what you might find at a gas station or convenience store.

Monitoring your home is both a comforting and frightening proposition. 

On one hand, it's nice to know the most possible information about your home, and feel secure even when you're not there. 

On the other hand, the idea that something in your house is watching you is a little creepy.

I saw both sides of the coin while testing out two Netatmo devices: Welcome, a camera with facial recognition capabilities, and Healthy Home Coach, a smart climate monitor. 

Here's what it was like. 

SEE ALSO: These $50 sensors are a useful, non-invasive way to keep your home safe

Let's start with the Healthy Home Coach. This device is about six inches tall and less than two inches wide. It plugs into a wall outlet and is able to monitor climate, humidity, air quality, and noise. The Home Coach costs $99.99.

I've had the Home Coach in my living room on the floor next to my couch for several weeks. It's slim and unobtrusive, so most of the time, I forgot it was there completely. The device only comes in copper, which looks a lot like rose gold in person.

Netatmo favors Apple-like finishes (brushed metal in silver, gold, and copper) and modern designs for all its smart-home products, which includes a smart smoke alarm, an outdoor security camera, security sensors for doors and windows (much like Notion sensors), a weather station, a smart thermostat, and more. 

You'll need to download an app in order to get the information the Home Coach is collecting. You can name your device within the app based on what room it's in — mine is just called "living room"— and watch as the device starts tracking different metrics.

You don't need to be at home for the device to collect information, and you don't need to manually sync your device with your app every time you want an update on the air quality. Once you set up the device and pair it with the app, it's essentially doing all the work for you. 

SEE ALSO: 'The Lost City of Z' is the best movie of 2017 so far

"Colossal"— April 7

Kaiju movies have a long and storied history in Hollywood, but "Colossal" looks like a fascinating twist on the formula. Centering on a young woman (Anne Hathaway) whose life is in shambles, the film follows her as she discovers that she finds that she is in complete control of a giant monster rampaging through Japanese cities. Early buzz on "Colossal" is almost universally positive, so all eyes are on this black comedy to take the monster movie genre in a very new direction.

"The Void"— April 7

The horror renaissance has been an absolute treat to watch unfold over the last few years, and it appears to be in full swing with the upcoming release of "The Void." A love letter to the 1980s (in the vein of "Stranger Things"), "The Void" centers on a group of people in a hospital surrounded by members of a violent cult as monsters begin to run wild. Expect practical effects and all of the blood and terror that you can take.

"The Fate of the Furious"— April 14

The "Fast & Furious" franchise continues to get faster and more furious, and it will once again come to a head when "The Fate of the Furious" hits theaters on April 14. Positioning Vin Diesel's Dom Toretto as the "villain" of the story, the eighth installment in the series has shifted its focus to give Dwayne Johnson's Hobbs and Jason Statham's Deckard Shaw the spotlight. Expect muscles, muscle cars, and an insane number of explosions when this one debuts.

It's wedding season, and that means that invitation you have hanging on your refrigerator door is likely going to be put to use soon.

Ergo, you're probably panicking about what to wear. Well, don't panic — we're here to help. We'll translate the invitation's instructions for you, with the help of longtime butler Charles MacPherson's etiquette guide "The Pocket Butler".

SEE ALSO: 22 clothing items every man should own before he turns 30

Black tie

Black tie is often considered the pinnacle of modern formality (aside from white tie, which has been completely forgotten about, and is almost never worn aside from royal weddings). Attendees of evening weddings are, however, sometimes requested to wear black tie.

If that's the case, here's what you need to wear:

- A completely black tuxedo with a white formal shirt featuring a wing collar, finished with a black satin bow tie. Sometimes a black satin cummerbund is added, but that is becoming less and less common.

- Black socks and black patent leather shoes are non-negotiable for footwear here.

Black-tie optional (also known as "formal")

If you see "black-tie optional" on a wedding invite, know that wearing a tuxedo is not required, but whoever sent the invitation will most likely be wearing one.

A wedding with a formal dress code means it's just slightly less formal than a black-tie wedding. It's up to you how closely you'd like to fit in.

- An appropriate black-tie optional outfit could include a navy suit with a formal dress shirt and a dark-colored tie (does not have to be a bow tie).

- Yes, you can wear a tuxedo if you'd like, and if the wedding is at night.

Cocktail attire

Cocktail is another step down from formal, which allows an injection of personality into what you're wearing.

We recommend you err on the side of caution and wear a suit here, but you don't have to. You could also get away with wearing a blazer and dress pants. Keeping it dark and seasonally appropriate will go a long way.

This is also what you should wear if there's no stated dress code on the invitation.

Project Scorpio is the third Xbox console that Microsoft has announced since the Xbox One.

Those consoles include the original Xbox One, which arrived in 2013; last year's Xbox One S, the same Xbox One with smaller, more attractive hardware; and now, the high-end Xbox console, Project Scorpio.

Whereas the Xbox One S can only play 4K video but not 4K video games, Project Scorpio boasts some pretty meaty specs to play super-high resolution 4K games and video, but whether you want to upgrade or not depends on a few things. One of those will surely be price, which Digital Foundry estimates to be around $500.

Project Scorpio will be able to play any games originally made available for the original Xbox One and Xbox One S, so aside from price, here are the circumstances when you could potentially justify upgrading to Project Scorpio (if you already own an Xbox One), or buying Project Scorpio when it comes out:

SEE ALSO: This is why you should (or shouldn't) buy an Xbox now instead of waiting for the souped-up 'Project Scorpio' coming later this year

1. If you already have a 4K TV.

If your living room sports a 4K TV and you're interested in 4K gaming, Microsoft promises that Project Scorpio will deliver. And if your 4K TV supports HDR, even better, because Project Scorpio will play games and video in HDR, too.

Even if you primarily just want to watch 4K videos and not play 4K games, you might as well get a machine that does both, just in case a game comes along that you really want to try in ultra-high resolution. 

If you own the original Xbox One and a 4K TV, it's worth upgrading to Project Scorpio to enjoy your games in all their glory. Or, even if you just recently got the Xbox One S, which was released in August 2016, you'll find value in trading it in (or selling it) for Project Scorpio. That's because the Xbox One S only plays video content in 4K, like TV shows and movies, but not video games — and video games are clearly a big chunk of the reason why someone would have a games console.

If you have a 1080p TV and you're not happy with the original Xbox One's (or Xbox One S') performance.

I remember when I first got my original Xbox One. It was a laggy, sluggish, hulking machine that generally played games at a lower resolution (albeit still being upscaled to 1080p) than the PlayStation 4. It hardly felt like a "next-gen" machine.

Several updates later, much has changed, and my original Xbox One feels a lot snappier and responsive. Still, Microsoft promises that game performance will be improved in the 1080p range, so if you want a better 1080p gaming console that potentially plays games at native 1080p rather than being upscaled from a lower resolution, Project Scorpio is for you.

If you've been thinking of buying a 4K TV.

If you've been thinking about buying a 4K TV, but you couldn't justify it because there isn't enough 4K content to play on it, Project Scorpio could be the machine that pushes you over the edge.

There isn't too much 4K video content out there to make the most of your 4K TV, but 4K console games could drastically fill up the currently-scant list of 4K content, especially if you play a lot of video games.

We'd suggest looking into 4K TVs with HDR to make the most of Project Scorpio's powerful new hardware.

Egg, cheese, and bacon or sausage: the classic breakfast sandwich.

It's ubiquitous, yet the simple breakfast sandwich enjoys eternal popularity.

And with breakfast habits changing, breakfast sandwiches on-the-go have become all the more popular. 

But of all the national chains, who makes the classic sandwich best?

I tried the egg, cheese, and meat iterations from three major fast-food chains — Burger King, McDonald's, and Wendy's — to see which one comes out on top.

SEE ALSO: We went to Red Lobster for its 'Endless Shrimp' promo and stayed for 8 hours — here's what happened

ALSO READ: We tested Panera against one of its biggest competitors — here's who emerges victorious

The Big Three all serve some version of the sandwich; at first glance the only difference seems to be the bread.

Let's dive into Burger King's Supreme breakfast sandwich. It's a breakfast limousine wreck of two eggs, two sausages, and two servings of bacon topped with cheese and served in a "toasted hoagie bun" which appears to be crushed in a car compactor before serving.

Source: Burger King

If this is a toasted hoagie bun, I don't know what a hoagie is. It's an elongated hamburger bun with all the sogginess and disappointment that buns are heir to — a bun to be wished away. The sickly yellow egg is gelatinous and tastes of complete nothingness. With fast-food sausage and bacon all in one sandwich, the entire thing comes off as incredibly salty. I didn't finish this one.

Travel has always been a part of Pedro Pla's life. By the time the Puerto Rican was three years old, he'd visited as many continents.

In 2007, Pla, now 35, and his Singaporean wife Grace Cheng, 36, embarked on a year-long journey around the world, traveling to 15 countries on five continents using two Round-The-World (RTW) economy tickets they'd purchased for around $10,000 through OneWorld, the network that comprises 15 international airlines.

To mark the 10th anniversary of their journey, the couple, now joined by their two sons, 4-year-old Ramses and 2-year-old Ranefer, set out on another trip around the world in January — but this time they got their tickets almost completely for free.

In September 2016, Pla and Cheng, who are the cofounders of credit-card comparison site Get.com, hit 1 million airline miles after a year of racking up credit card rewards points. They redeemed 960,000 miles, worth a total of $54,000 (though they had to cover taxes and fees), through Singapore Airlines' frequent flyer program, KrisFlyer, to purchase four RTW business class tickets.

Singapore Airlines is part of the Star Alliance network, which has more than two dozen regional and international carriers. The RTW ticket allows travel on any airline in the network, up to 35,000 miles in a continuous Eastbound or Westbound direction on 16 separate flights. The cost of a RTW ticket can vary depending on the flight class, country of origin, and total mileage of the trip. Tickets can be purchased in cash or redeemed through points and can only be booked over the phone.

On their six-month trip, the family is traveling to five continents and at least 15 countries, including Kenya, Switzerland, Argentina, Colombia, and South Korea.

"While booking our Round-The-World flights with SIA, its customer service representative told us we had 'hit the jackpot' as they had never encountered anyone redeeming for RTW award tickets on business class before, let alone for four people," Pla told Business Insider in an email.

He said they had to "research and plan meticulously" to reach their points goal.

"As credit card geeks, we live by this maxim: When you use cash, you lose cash. Using cash means you are missing out on getting credit card rewards points, miles or cash back. We used our credit cards to pay for everything if possible, be it a hamburger or an air ticket," Pla said.

Read on to learn more about the RTW program, exactly how the family racked up their rewards points, and their best advice for travel hacking.

Follow the family's Round-The-World journey on their Instagram or Get.com.

SEE ALSO: The values of credit card, airline, and hotel points can vary wildly — and there's a website that keeps track of them all

DON'T MISS: A 30-something travel hacker who spent 11 years exploring 193 countries reveals which travel rewards card he uses every day

The RTW program — which is offered by each of the three big airline networks, Star Alliance, SkyTeam, and OneWorld — allows you to travel up to a certain amount of miles or stops and typically costs less than buying individual flights, Pla explained.

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 The couple and their two sons awaiting take off at Singapore Changi Airport.

They booked through Singapore Airlines, part of the Star Alliance, after transferring all their rewards points to KrisFlyer, the airline's frequent flyer program. One RTW ticket in business class costs 240,000 miles, so the family of four needed 960,000 miles.

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 The family in the Maldives.

"When redeeming for miles it makes a lot more sense to get business or first class tickets," Pla said. "In this case the RTW ticket was 240,000 miles for business and 120,000 miles for economy. However, if purchasing the segments themselves, they can cost 3-5 times as much for business versus economy, so it's a much better deal to redeem miles for business class tickets instead of economy."

The INSIDER Summary:

• Victoria Beckham's new collaboration with Target launches on April 9.
• The line features 200 pieces, including plus sizes.
• Historically, Target's designer collabs have sold out within a matter of hours, so move fast.

When Victoria Beckham announced she'd be collaborating with Target to release a 200-piece collection, we were super excited.

When we found out the line will include plus sizes, we were THRILLED.

Now, the collection is set to be available for purchase on April 9. Historically, Target's designer collabs have sold out within a matter of hours (demand for the Lilly Pulitzer line even crashed the site), so you need to know what you want in advance.

We've rounded up the 10 must-have pieces from Victoria Beckham's Target line. Happy shopping!

Blush Collared Dress

We can't resist the blush color on this cute, work-appropriate dress (the collection actually focuses heavily on business casual attire). A bunny print on the collar adds a fun twist.

Women's Blush Collared Dress from Victoria Beckham for Target, $35
Women's Plus Blush Collared Dress from Victoria Beckham for Target, $35

Floral Photo Skirt

If you've ever seen "The Devil Wears Prada," you know that florals for spring aren't exactly groundbreaking. However, this skirt takes florals literally, by printing an actual photo of flowers on the fabric. We love this fresh take on a classic trend.

Women's Black Satin Photo Floral Skirt from Victoria Beckham for Target, $30

Bee Print Shirt

Bees have become trendy as the fight to save them has become more urgent. Again, this top is totally work appropriate, but the fun print makes it stylish as well. 

Women's Bee Print Button Down Top from Victoria Beckham for Target, $30
Women's Plus Bee Print Button Down Top from Victoria Beckham for Target, $30