To actually walk on the ramparts of Cité Médiévale, you have to pay to enter the Château et Remparts, a keep built for the viscounts of Carcassonne during the 12th century. Admission includes access to the keep’s rooms and a section of the battlements, with fabulous views over the surrounding countryside and the distant Pyrenees. Tours in several languages are available in summer; check with the tourist office for schedules.