In downtown Rome, on Via Veneto very close to the US Embassy, is Santa Maria della Concezione. Beneath it is what is commonly called the Capuchin Crypt.
It contains the bones of hundreds of long-dead Capuchin monks, "artfully" arranged into sculptures and other sorts of designs in 4 or 5 rooms.
It is macabre almost beyond description. I go there almost every time I'm in the city.
http://www.twenj.com/rometour4.htm#crypt