Eastern State Penitentiary is an old prison within the city limits of Philadelphia. It is a quick walk from the downtown hotels in an up and coming neighborhood. We went in January when it was quite cold, but it was still a great day to take a tour of the prison. For a small charge you can do a self-guided audio tour with a headset. You are allowed to explore a significant portion of the prison and even go into some of the cells. Al Capone's cell was a highlight as it was very nice by prison cell standards. We went early in the morning so not many people were there, and it had a very eerie feeling. I would highly recommend going to see this if you are in Philadelphia and looking for something to do!