Barnstable Old Gaol is a historic jail located in Barnstable, Massachusetts. Built in 1690, it is one of the oldest surviving jails in the United States. The structure is made of local stone and features a simple design typical of colonial architecture. It served as a prison until 1820 and housed various inmates, including those accused of minor crimes. Today, the Old Gaol is preserved as a museum, offering visitors a glimpse into colonial life and the early justice system. Guided tours provide insights into the building's history and the stories of its former inmates, making it a significant landmark in Cape Cod.