Beaumaris Gaol

This grim, stout-walled jail, opened in 1829 and largely unaltered since, was modern for its time, with toilets in every cell and a treadmill water pump. However, that's not enough to dispel the gloom of the windowless punishment cell, where condemned prisoners awaited their demise at the gibbet, or the stone-breaking yard where inmates were subjected to hard labor. Since it closed as a jail, it's been used as a children's clinic (cheery!) and a police station.