Circus Circus was opened on October 18, 1968 by Jay Sarno, becoming the flagship casino for Circus Circus Enterprises. Architects Rissman and Rissman Associates designed a giant circus tent shaped main structure, which was built by R.C. Johnson Construction of Las Vegas.
At its opening, the $15 million facility only included a casino. The lack of a hotel resulted in financial problems, as the casino was not able to attract high rollers. Sarno obtained a $23 million loan from the Teamsters Pension Fund to construct a hotel. As part of the arrangement, the Chicago Outfit's enforcer, Anthony Spilotro (under the name of Tony Stuart) was granted a gift shop concession in the hotel. In addition to a government investigation into the organized-crime connections, Sarno was also being investigated for tax code violations. The casino's financial problems also continued and Sarno, along with his partner Stanley Mallin, decided to sell out.
In 1974 ownership changed with the sale of the casino to William Bennett and William Pennington for $25 million. The facility was expanded with hotel tower additions in 1972, 1980, 1985 and 1986 and 1996.
In his journalistic novel of the early '70s, Fear and Loathing in Las Vegas, Hunter S. Thompson wrote, "The Circus-Circus is what the whole hep world would be doing Saturday night if the Nazis had won the war. This is the sixth Reich. The ground floor is full of gambling tables, like all the other casinos . . . but the place is about four stories high, in the style of a circus tent, and all manner of strange County-Fair/Polish Carnival madness is going on up in this space." When the Thompson work was adapted to film in 1998, the fictional "Bazooko Circus" was a thinly-veiled stand-in for the world-famed resort, which had refused permission for the filmmakers to shoot on their property.
The Adventuredome Theme Park and the Canyon Blaster roller coaster were featured in the 1999 movie Baby Geniuses. The theme park was known as Joyworld in the movie.