6. Eastern State Penitentiary, Pennsylvania Most of the prisons on this list are either completely abandoned or have been demolished by now; Philadelphia's Eastern State Penitentiary is an exception. There are tours here and it is open as a museum. Make no mistake, though, the decay and feeling of abandonment still pervades this place, which once held such notable figures as Al Capone. Notions of reform and Christian faith were built into the design and theme of the prison: cell doors were small, forcing prisoners to bow to enter, and there was only a single skylight, representing the "Eye of God", in each cell.