The towers can be seen from inside the holy mosque of Mecca, where crowds flock to pray.
Inside, there are restaurants, a five-story shopping mall, luxury hotels and condos, and a parking garage.
At the peak, there's a massive gold-painted crescent, which appears in white on Mecca's flag.
The tallest tower (at 120 stories) features the world's largest clock face.
next slide will load in 15 secondsSkip AdSkip AdAt a whopping $15 billion, the Abraj Al Bait features seven towers completed from 2007 to 2012. Located in Mecca, the Saudi Arabian government owns the complex.
With a cost of $5.7 billion, it's billed as one of the world's most expensive casino properties, though it also includes a hotel, a convention center, a mall, a museum, two theaters, seven restaurants, and a skating rink.
Three towers make up the Marina Bay Sands Resort, which opened in 2010 in Singapore.
Here's what it looks like inside. In 2016, it started a $1.6 billion expansion, set to be finished in 2020.
With a price tag of $4.1 billion to construct in 2005, the 614-foot-tall Wynn resort and casino sits on the Las Vegas Strip.
next slide will load in 15 secondsSkip AdSkip AdOne of the Cosmopolitan's main attractions is its giant glowing chandelier. There's also a casino, shops, restaurants, a theater, a gym and spa, and a convention space.
In 2010, a set of Las Vegas high-rises called the Cosmopolitan was built for $3.9 billion.
In the elevator going up to the observation deck, there's a timelapse projection that shows what Manhattan has looked like every year since 1500.
With a price tag of $3.8 billion, One World Trade Center opened in 2012. Located in New York City, it's next to the site of the original WTC, which is now a memorial for the victims of the September 11 attacks.
In the center of the mall, there's a manmade "river" (modeled after the famous one in Venice), where shoppers can take gondola rides.
next slide will load in 15 secondsSkip AdSkip AdThe Venetian is a luxury hotel, mall, and casino in Macau. Built in 2005, the 738-foot resort cost $2.4 billion.
The view from the higher floors is stunning.
Constructed in Dubai in 2012, the $2.17 billion Princess Tower houses shops and 763 luxury condos.
Italian Renaissance architecture influenced the hotel and casino's design.
Built in 2007, the $2.05 billion Palazzo Casino is on the Las Vegas Strip.
next slide will load in 15 secondsSkip AdSkip AdThe skyscraper features a giant sphere painted gold, which spans its 87th through 92nd floors. The other levels contain offices, shops, and a restaurant.
Stretching 101 stories, the aptly named Taipei 101 was built in 2004. It hovers over Taiwan and cost $1.8 billion.
The tallest building in the UK, it features residences, a hotel, restaurants, offices, a business school, shops, a clinic, and an observatory.
London's glass Shard, completed in 2012 for $1.5 billion, is a 95-story skyscraper.
The twin skyscraper houses the headquarters of the ECB, the central bank for the euro.
next slide will load in 15 secondsSkip AdSkip AdThe Seat of the European Central Bank (ECB) in Frankfurt, Germany cost $1.25 billion to construct in 2013.
Including the antennae, the tower stands 2,717 feet tall, making it the tallest building in the world. Inside, there are residential apartments, eight hotels, shops, restaurants, and offices. Here's the view from the observation deck (also the world's tallest):
The Burj Khalifa in Dubai cost approximately $1.5 billion to build. Construction lasted from 2004 to 2009.
The second floor features a shopping mall, bank, and mosque, designated only for women. Designed by Minnesota-based firm Ellerbe Necket, the Kingdom Centre also includes a hotel, offices, apartments, and a 184-foot skybridge.
Located in Riyadh, Saudi Arabia, the Kingdom Centre cost approximately $1 billion to build. Construction of the 990-foot skyscraper wrapped up in 2002.
next slide will load in 15 secondsSkip AdSkip AdAt $1 billion, Antilia is the world's most expensive residential property behind Buckingham Palace. It's also designed to survive a magnitude 8 earthquake.
In 2006, Indian business magnate Mukesh D. Ambani built the 27-floor Antilia skyscraper, which serves as his private residence.
The 1,483-foot-tall skyscrapers reportedly cost approximately $1 billion total and contain 88 floors each, made up of offices and retail stores.
The Petronas Twin Towers, located in Malaysia, was constructed in 1999.
The $1 billion building thins toward the peak and features sharp edges.
next slide will load in 15 secondsSkip AdSkip AdIn Hong Kong, the Bank of China completed its 1,204-foot-tall headquarters in 1990.