Need Map: Chateau d'If style prison

[Tumbler]

I am wanting to send my characters off to a prison for the politically unpopular like Chateau d'If in "The Count of Monte Cristo." I could use a good map of such a prison, or any island fortress with some places to lock people up, whether towers or dungeons, preferably both. I need a fairly detailed map so they can explore, gather resources, and find a way off of the island.

 

[Phineas Crow]

My River Castle map may make an interesting prison fortress.