High Quality Content by WIKIPEDIA articles! Walnut Street Jail, named after the Philadelphia, Pennsylvania street on which it was located, was the first jail built in the United States.In 1776, in Philadelphia, Pennsylvania, the first jail in America was built. It was located on Walnut Street where it acquired the name Walnut Street Jail. The jail was designed to hold groups of inmates in large rooms. It was designed by Robert Smith. He was one of the most prominent architects in Philadelphia. The building was in the typical U-shape designed to hold large numbers of inmates. There was little regard for their physical well-being, nor were there any attempts to rehabilitate them. Prisons were overcrowded and dirty, and inmates attacked each other regularly. Those who served their sentences came out of prison probably more inclined toward a criminal life than they were before their incarceration. Some fifteen years later, an addition was made to the jail. They added a new cellblock and called it the "penitentiary house". Built in the courtyard of the existing structure, it included a series of small cells designed to hold individual prisoners.