A circus was the site of performances by various acts. The travelling nature of circuses made tents a popular choice for their infrastructure.
The acts often included conjurers, acrobats, clowns, bearded women and performances by animals, such as elephants. (TV: Terror of the Autons, Escape to LA)
The Third Doctor visited Luigi Rossini's International Circus after learning of the Master's activity there. (TV: Terror of the Autons)
In May 1884, the Judoon Captain Kybo was exhibited as part of the freakshow at Jonathan Jaggers' circus in Reigate, England. (AUDIO: Judoon in Chains)
When the Twelfth Doctor and Clara Oswald visited Blackpool in 2089, they encountered wild giraffes, parrots and lions which had escaped from the circus. (PROSE: All the Empty Towers)
The Psychic Circus was taken over by the Gods of Ragnarok on Segonax. (TV: The Greatest Show in the Galaxy)