Ruthin Gaol is a Pentonville style prison in Ruthin, Denbighshire. Ruthin Gaol ceased to be a prison in 1916 when the prisoners and guards were transferred to Shrewsbury. The County Council bought the buildings in 1926 and used part of them for offices, the county archives, and the town library. During the Second World War the prison buildings were used as a munitions factory, before being handed back to the County Council, when it was the headquarters of the Denbighshire Library Service.