Prisoners in Halden's maximum security prison Norway

Designed by John Haviland and opened on October 25, 1829, Eastern State is considered to be the world's first true penitentiary. Eastern State's revolutionary system of incarceration, dubbed the "Pennsylvania system" or separate system, encouraged separate confinement as a form of rehabilitation. The warden was legally required to visit every inmate every day, and the overseers were mandated to see each inmate three times a day.

The Pennsylvania system was opposed contemporaneously by the Auburn system (also known as the New York system), which held that prisoners should be forced to work together in silence, and could be subjected to physical punishment (Sing Sing prison was an example of the Auburn system). Although the Auburn system was favored in the United States, Eastern State's radial floor plan and system of solitary confinement was the model for over 300 prisons worldwide. Critic and activist John Neal in 1841 expressed revulsion at the international reputation of "a nation that broke away from all its bands and fetters, only fifty or sixty years ago — overthrowing prisons, palaces, and thrones in her march toward universal emancipation, already renowned throughout the whole earth, for her prisons, her manacles, and her badges of servitude."

Originally, inmates were housed in cells that could only be accessed by entering through a small exercise yard attached to the back of the prison; only a small portal, just large enough to pass meals, opened onto the cell blocks. This design proved impractical, and in the middle of construction, cells were constructed that allowed prisoners to enter and leave the cell blocks through metal doors that were covered by a heavy wooden door to filter out noise. The halls were designed to have the feel of a church.

Some believe that the doors were small so prisoners would have a harder time getting out, minimizing an attack on an officer. Others have explained the small doors forced the prisoners to bow while entering their cell. This design is related to penance and ties to the religious inspiration of the prison. The cells were made of concrete with a single glass skylight, representing the "Eye of God", suggesting to the prisoners that God was always watching them.

Outside the cell was an individual area for exercise, enclosed by high walls so prisoners could not communicate. Exercise time for each prisoner was synchronized so no two prisoners next to each other would be out at the same time. Prisoners were allowed to garden and even keep pets in their exercise yards.

https://en.wikipedia.org/wiki/Eastern_State_Penitentiary#History