Las Vegas is home to some of the most extravagant hotels ever built. They are a marvel of modern design and engineering filled to the brim with luxury, world-class food, and, of course, thousands and thousands of slot machines, poker tables, and roulette wheels. Just taking a walk through these monstrous mega-hotels is enough to draw visitors from around the world. It should come as no surprise that to build hotels like these, costs can easily surpass the billion-dollar mark. Here are five of the biggest and most extravagant hotels ever built in Sin City.

5. MGM Grand

MGM Grand hotel in Las Vegas surrounded by palm trees.
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Estimated cost: $1.1 billion

The MGM Grand is the largest single hotel in the United States with more than 6,500 rooms. Building something that impressive takes some serious money. Kirk Kerkorian was the original builder of the hotel. He was also the owner of Metro-Goldwyn-Mayer, which you might know from the roaring lion at the beginning of some of your favorite movies.

It cost a record-setting $1.1 billion to construct the massive edifice. Adjusted for inflation, that price hits almost $2 billion. The hotel as we know it today opened its doors in 1993. At the time, it was the largest hotel complex in the world. It has more floor space than even the Empire State Building! Millions of travelers visit the hotel and casino each year, and it was once robbed by George Clooney and Brad Pitt along with nine of their friends... at least, on film.

4. The Palazzo

The Palazzo resort and casino complex in Las Vegas, Nevada, lit at night
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Estimated cost: $1.5 billion

The Palazzo is a hotel and casino complex that includes the Venetian Resort and Casino along with the Sands Convention Center. Combined, it is the largest hotel complex in Las Vegas and the second largest in the world. In total, there are 7,117 rooms available for guests.

The hotel was built with an Italian Renaissance ambiance. It lives up to its Venetian name by having canals that run through the middle of the hotel complete with gondola rides. The mega-hotel opened its doors in 1999 and cost $1.5 billion to construct. In 2019, that cost would be equivalent to $2.3 billion.

3. Bellagio Hotel

Colorful night view of the Bellagio hotel and casino with water fountains, Las Vegas, Nevada
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Estimated cost: $1.6 billion

At the time of its opening in 1998, the Bellagio was the most expensive hotel ever built. In front of the building sits the world-famous Bellagio fountains that contain 1,214 jets that shoot water 460 feet above the massive 8.5-acre artificial lake. The fountain is choreographed to several popular songs. The best part: It’s completely free to see the show! Just stand on the sidewalk outside and take it all in.

When it was completed, the Bellagio set owner Steve Wynn back $1.6 billion, which would be almost $2.5 billion by today’s standards. It was later bought out by MGM and was another property featured in the popular movie “Ocean’s Eleven.”

2. Wynn Las Vegas

Street view of the Wynn and Encore hotels as the sun sets with palm trees out front, Las Vegas, Nevada
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Estimated cost: $2.7 billion

One of the most visually striking hotels on the Vegas Strip, the Wynn opened its doors in 2005. Owner Steve Wynn was a Las Vegas hotel veteran who had already built the Mirage in 1989 and the Bellagio in 1998. He sold them both to construct his most ambitious creation yet.

The Wynn cost $2.7 billion to build, which is equivalent to $3.5 billion in today’s standards — a full $1 billion more than the next most expensive hotel on the list. Not content with just one mega-hotel, Wynn built a $2.3 billion replica next door three years later and called it the Encore.

1. Cosmopolitan

Night view of the Cosmopolitan skyscraper resort on the Las Vegas Strip, Las Vegas, Nevada
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Estimated cost: $3.9 billion

The Cosmopolitan, or Cosmo for short, was originally supposed to be a condominium building. Those plans fell through, and it became another hotel. But what sounds like an unfortunate change of plans turned out to be a bonus. Since the rooms were supposed to be apartments, the Cosmopolitan has some of the largest accommodations in Las Vegas, giving visitors more bang for their buck. Its casino is also smaller and easier to navigate compared to its massive neighbors, much to the delight of its customers. People seem to love it because it’s different and not just another behemoth.

The hotel was completed in 2010 to the tune of $3.9 billion, which is equal to $4.5 billion in 2019, making it the single most expensive hotel ever built in Las Vegas by a wide margin and fourth most expensive hotel in the world.