Astley's Amphitheatre was a performance venue in London opened by Philip Astley in 1773, considered the first modern circus ring. It was burned and rebuilt several times, and went through many owners and managers. Despite no trace of the theatre remaining today, a memorial plaque was unveiled in 1951 at its site at 225 Westminster Bridge Road.

Philip Astley was an English equestrian, circus owner, and inventor, regarded as being the "father of the modern circus". Modern circus, as an integrated entertainment experience that includes music, domesticated animals, acrobats, and clowns, traces its heritage to Astley's Amphitheatre, a riding school that Astley founded in London following the success of trick-riding displays given by him and his wife Patty Jones in 1768. Astley's first competitor was equestrian Charles Hughes, who had previously worked with Astley. Together with Charles Dibdin, a famous author of pantomimes, Hughes opened a rival amphitheatre in London, which Dibdin called the Royal Circus and Equestrian Philharmonic Academy.