Wall of Death
The Wall of Death is a completely and utterly bananas circus act that you may not have heard of — but rest assured it's still performed today, some eight or nine decades after it originated [source: Original Wall of Death]. The Wall of Death is a motor-sports act where motorcycles or cars race around the walls of a cylinder ring while performing trick stunts. It's straight-up terrifying to watch, let alone take part in.
It's not a part of every circus (and perhaps for safety's sake we should be grateful), but it's one in a long line of exhibitions that have become a popular staple of entertainment. It uses centrifugal force and inertia to keep riders on the curvature of the wall. The Wall of Death was originally even more dangerous, with less-sloped walls on a mile-long track, and riders and spectators alike died during performances [source: Robbins]. Performers are still putting themselves at serious risk today. Samantha Morgan, a pioneer Wall of Death rider, died in 2008 of complications from her injuries over the years.