Located within the Château Comtal, visiting the museum is the only way to gain access to the chateau. The collection Roman and medieval artifacts is interesing. My favorites are the old gravestones, the round stone missiles (they look like cannon balls, but are of stone) use for catapults. Also impressive are the murals on the walls of one room in the chateau.
A curiosity to me is the miniature replica of Carcassonne. Instead of looking at a replica, why not just look around you?
Important piece of art depicting Christ. The Museé Lapidaire can be found at the Chateau Comtal within the walls of Carcassonne Old Town.