Once the county's main prison, this forbidding place is now notorious for the numerous ghosts said to haunt it. Though much of the original jail has fallen into ruin, some sections of the jail are still open to the public: you can wander around several cells, populated by rather lame mannequins depicting episodes of penal life (some of which, such as the working execution pit, are pretty macabre). Late-night ghost walks are held several times a year.
There's also a restaurant and shop onsite.
Plans to redevelop parts of the jail into a luxury hotel have so far come to naught, but watch this space.