Due north of Carcassonne, just a little over two hours away from Toulouse, are the Lastours Castles (Châteaux de Lastours). Not much more than ruins now, during the height of Catharism in the 13th century these four castles played a major role in the defense of, access to and passage through the area.
The Lastours Castles each have a name: Cabaret, Quertinheux, Surdespine and Tour Régine. Perhaps most astounding to visitors is their location, situated as they are on an alarmingly narrow ridge. Equally surprising is that archaeologists continue to find historical artifacts near the castles that tell us more about the Cathars.
The Lastours Castles are closed to visitors from Jan. 1 to Feb. 15. March has wildly varying opening days and hours, so check ahead before going. In April through October, the castles are accessible every day from roughly 10 a.m. to 6 p.m., with a later closing time of 8 p.m. in July and August. Then in November and December, there are again extremely varied hours, so it's good to check ahead.