On a recent trip to Philadelphia, I stopped at the Eastern State Penitentiary. Opened in 1829, this was the most famous and expensive prison of its time. Tourists and researchers came from around the world to study this innovative prison system, including Alexis de Tocqueville and Charles Dickens.

Eastern State Penitentiary was famous because it focused on encouraging penance, rather than punishment, thus coining the term “penitentiary.” Prisoners were isolated in separate cells and kept in silence in order to reflect on their behavior and become penitent. The guards watched the inmates from a center rotunda with the seven cell blocks radiating from the middle. Each prisoner had his or her own cell, running water, flush toilet, skylight, and outdoor exercise yard.