The Cosmos Casino was a casino in Las Vegas from 1962 to 1963, which was used as a front for the criminal Kronos Family.
The casino was shaped like a giant rocket, and had a space-age interior aesthetic. Since the Kronos Family were members of the Cybock Imperium who were hiding on Earth from the Alliance of Races, the Twelfth Doctor thought their design choices were not very subtle.
As well as concealing the Cybok's base, which included a spacecraft hangar and a holding room for prisoners, the casino generated profit which the Kronos Family could use to increase their influence across the city. (COMIC: Gangland)