All of the ground floor cells at Eastern State Penitentiary were originally linked to a private exercise yard. Prisoners could access this for 30 minutes twice a day, although otherwise they had to remain in their cell. Eventually this policy fell out of favour and the exercise yards were either repurposed or demolished.
This exercise yard is one of the very few which has survived with its original walls, solely because it was later used as a bathroom for the neighbouring exercise yard. The doors to the exercise yard are still though visible at the rear of most cells as they were just blocked off.