York Castle Museum is a museum located in York, North Yorkshire, England, on the site of York Castle, which was originally built by William the Conqueror in 1068. The museum itself was founded by John L. Kirk in 1938, and is housed in prison buildings which were built on the site of the castle in the 18th century, the debtors' prison (built in 1701–05 using stone from the ruins of the castle) and the female prison (built 1780–85).