The Ossaville Castle is a castle built on the peak of a mountain 2 miles from the town of Ossaville, west of Gotham City. Jean-Paul discovered the location while pursuing Sister Lilhy and the Chinese Azrael that was serving the insane Jeremiah Thompkins.
Built by the Order of St Dumas, the castle was converted to serve as Jean-Paul Valley's lair; with Harold Allnut operating as his mechanical engineer.
The castle served as Jean-Paul's home base as he sought to help whomever needed assistance.
The castle was destroyed when Jean-Paul planted explosives within the caverns after having fallen sway to the System.