The E.S.P. was the beginning of the "Pennsylvania Style" prisons. They were very popular world wide for quite some time, and are even used in some countries to this day. They are designed like a spoke and wheel. The idea was that a guard could stand in the center of the prison and see down all of the cell blocks.
Over time the idea for single story and solitary holdings needed to be abandoned. Not only were they running out of room, but they also began to realize that rehabilitation of prisoners was not going well when they were in solitary all of the time.
The common yard was small and quickly outgrown. This is part of the baseball diamond.
Originally all of the prisoners had their own private exercise "yards." This was how they were brought into and out of their cells. As the orginal doors from the inside were only large enough to fit food through. Prisoners were originally brought in with hoods over their heads so they could not get a feel for where they were in the prison and could not see any other prisoners.