“An experiment in penology,” according to Sanford Bates, director of the Bureau of Prisons, Northeastern Penitentiary was based on the belief that the prison environment could contribute to the rehabilitation of the prisoner. To that end, Hopkins, foremost prison architect in the United States, modeled the building after the Palazzo Pubblico in Siena with its surveillance tower and famous mural series analyzing the role of democratic institutions in maintaining law and order. Hailed as “the world's most modern penal institution,” its flaws soon became apparent. The plan obstructed supervision and inmates had easy access to the bars placed on the inside of the windows to maintain the building's aesthetic integrity. Nevertheless, the underlying concept was noble, and as Bates observed, it was “extremely pleasing from an architectural point of view.”