Poveglia, Italy - a small island in the Venice lagoon, with a few partially-standing but decrepit structures, and absolutely
brilliant for your horror/supernatural game.
*) Abandoned in the 1300s due to war, and mostly unrepopulated when the existing buildings were reduced to ruins.
*) Used as a plague island -- basically a death sentence to be sent there. Hundreds of people a day were said to die there, cremated and the ashes scattered.
*) Site of battles during the Napoleonic era after it was used as a weapons depot.
*) And
of course after all of this a mental hospital was opened there in 1922. The poor inhabitants would frequently insist that they were seeing the ghosts of the plague victims. Supposedly medical experiments were performed there -- lobotomies and the like -- and the head doctor threw himself from the bell tower of the old church there, claiming the patients had driven
him mad.
The mental hospital closed after this event, in 1968, and since then the island has been completely deserted. The locals regard it as haunted and evil beyond description, and even fishermen avoid the surrounding waters.
Good gaming to you...