The Strat (formerly the Stratosphere) is a hotel and casino in Las Vegas, Nevada, United States. It includes a 1,149 ft (350.2 m) observation tower, the tallest in the United States. It is also the second-tallest observation tower in the Western Hemisphere, surpassed only by the CN Tower in Toronto, Ontario. The top of the tower includes a revolving restaurant, lounges, observation decks, and several thrill rides. The hotel and casino are at the base of the tower, and the resort also includes a showroom and a shopping mall. The Strat is within city limits on Las Vegas Boulevard, just north of the Las Vegas Strip. The resort is sometimes considered a Strip property, but Clark County does not officially recognize it as such, saying the Strip does not extend into the city.

Part of the property was previously occupied by Vegas World, a hotel and casino Bob Stupak opened in 1979. A decade after its opening, Stupak announced plans for a giant neon sign for Vegas World, to be built on adjacent property. The idea soon evolved into an observation tower with a rooftop restaurant. Construction of the Stratosphere Tower began in 1992. A fire of unknown origin occurred on the tower in August 1993, during construction. Stupak then had difficulty acquiring funds to finish the tower. To complete the project, he partnered with Grand Casinos, owned by his poker friend Lyle Berman.

The tower was originally proposed with a height of 1,012 ft (308 m). But in 1994, Stupak considered extending the height to 1,825 ft (556 m), seeking the title of tallest free-standing structure in the world. The Federal Aviation Administration opposed the new height, and the city ultimately rejected it, but allowed Stupak to go as high as 1,149 ft (350 m). Vegas World closed on February 1, 1995, and its hotel towers were remodeled to serve as the hotel for the Stratosphere. New hotel towers were built to accompany the existing buildings. The observation tower, which cost $70 million to build, was topped off on November 4, 1995.

The $550 million Stratosphere complex opened on April 30, 1996. Parts of the resort were unfinished at the time, including a hotel tower and sections of the shopping mall. The Stratosphere was built in a crime-ridden neighborhood known as Naked City. The resort struggled financially during its first year for a number of reasons, including its location away from the Strip and other resorts. Marketing was also limited, as Berman initially believed the tower had generated enough publicity on its own. The unfinished facilities were another factor in the resort's low revenue.

Stratosphere Corporation filed for Chapter 11 bankruptcy in 1997, and businessman Carl Icahn purchased the resort in 1998. Icahn had the remaining hotel rooms finished in 2001 as part of a $65 million renovation project. The resort became profitable under his ownership by targeting value-conscious visitors. In 2004, ownership was transferred to Icahn's company, American Casino & Entertainment Properties (ACEP). Whitehall Street Real Estate Funds purchased ACEP and the Stratosphere in 2008. Two years later, ACEP carried out a $20 million renovation that included remodeling the hotel rooms. Other renovations continued into 2012. Golden Entertainment purchased ACEP and the Stratosphere in 2017, and additional renovations began in 2018, continuing into 2020. The resort was rebranded as The Strat on January 22, 2020.

In 1974, Bob Stupak opened a small casino in Las Vegas known as Bob Stupak's World Famous Million-Dollar Historic Gambling Museum and Casino, north of the Las Vegas Strip on land previously occupied by the Todkill/Bill Hayden Lincoln Mercury Dealership. The casino burned down two months later, and Stupak opened his Vegas World hotel and casino on the same property in 1979.

Stupak's concept for the Stratosphere began as a plan to construct a 1,012-foot (308 m) neon sign tower for Vegas World. In October 1989, Stupak submitted plans to the city for the approval of the neon sign tower, which would stand four times taller than the hotel. A few days later, he withdrew his plans to allow time for a revised version of the tower that would include an elevator leading up to an observation deck. Stupak, who wanted the tower to become a local landmark, said, "What I'm trying to do for Las Vegas is what the Eiffel Tower did for Paris, what the Empire State Building did for New York, what the Seattle Space Needle did for Seattle." Stupak's plans received widespread opposition, including from Las Vegas city staff, who drafted an ordinance that would have limited signs to 35 feet. The Las Vegas City Council rejected the ordinance, considering it a poorly drawn measure aimed specifically at stopping Stupak's project.

In February 1990, Stupak unveiled his revised plans for a $50 million, 1,012-foot (308 m) observation tower with a top floor that would include a revolving restaurant and four penthouse suites. It would be the tallest structure in Las Vegas and in Nevada. The tower was designed by architect Ned Baldwin, who also worked on the CN Tower in Toronto. Stupak's vision for the project was inspired by the Sydney Tower in Australia, where he once lived. In April 1990, the city council approved Stupak's tower, despite objections from the Federal Aviation Administration (FAA), which said it was 200 feet (61 m) too tall. Nellis Air Force Base also opposed the tower. Stupak later said that "all sorts of people out there opposed" the tower, adding, "If it wasn't for the courage of the council, it would have never been built." Critics later called the project the "eighth blunder of the world" and "Stupak's shaft."