The walls at Eastern State Penitentiary are all but unscalable all the way around. In 1945 a group of 12 inmates dug a secret 97 foot tunnel underneath the wall. The infamous bank robber Willy Sutton was among the dirty dozen to escape.
Imagine for a moment that you are a prisoner at Eastern State Penitentiary. The only natural light you see for 23 hours of the day is what shines through the hole in your roof. You are required to remain absolutely silent or face stiff punishment. What would this do to your sanity?