Astley's Amphitheatre

You are walking over the ground where the modern circus was born. Philip Astley, a former cavalry sergeant major, discovered that by galloping his horse in a tight, forty-two-foot circle, he could use centrifugal force to stand upright on the horse's back while performing daring stunts. He opened this arena in 1768, and that specific forty-two-foot diameter remains the international standard for circus rings to this day.