The Dubuque County Jail is an historic building in Dubuque, Iowa. The National Park Service describes it: "Completed in 1858, this massive stone building was designed by the Midwestern architect who also did such masterpieces as the Old Illinois State Capitol. An outstanding example of the Egyptian Revival style, it exemplifies the antebellum penal reform movement in the United States." The main architect, John F. Rague, also designed the 1837 Old Capitol of Illinois and the 1840 Territorial Capitol of Iowa.
The jail is famous for having at one point hosted Butch Cassidy, who was picked up outside of Dubuque on his way back to Wyoming from Chicago. It was thought he had robbed a bank on the Illinois side of the Mississippi, but no one was willing to testify against him and no evidence was found at the scene to link Cassidy with the robbery, so he was let free after only four hours in detention. He was never formally charged.
The Dubuque County Jail currently houses the Old Jail Museum, which is operated by the Dubuque County Historical Society. The museum exhibits part of the Society's collection of local history artifacts, as well as a sound and light show, "The Hanging of Patrick O'Connor", about a local murder and execution which occurred 20-yards from the jail.