sights of carcassonne.

http://www.tourisme-carcassonne.fr/decouvrir/patrimoine-culturel-et-religieux/la-cite-medievale

Traveling this region one can enjoy the landscapes and scenery of the mystical Cathar country. For those who are found of old cultures and history there are the many Cathar  castles to visit: Lastours, Saissac, Termes, Puivert... and not to forget the medieval city of Carcassonne that recently became part of the world heritage sites of the Unesco, -just as the Canal the midi-, Carcassonnes medieval city is also the spot for the famous theatre festival , each year  during the month of July. 

http://www.chateauxdelastours.fr/topic/index.html

The Aude region also offers some very impressive abbeys to visit: Fontfroide, Villelongue, Lagrasse, Saint-Papoul, Saint-Hilaire, Saint-Polycarpe, Caunes-Minervois...

http://www.gouffre-de-cabrespine.com/fr

In La Montagne Noire you also have interesting natural sites such as the Gouffre Géant de Cabrespine: an outstanding cave of national renown and the Grotte de Limousis.

Some very nice villages and cities worth a visit: Castres, Lautrec, Carcasonne, Limoux (famous for it's Blanquette and carnival), Narbonne and Gruissan on the coast.