The city of Carcassonne is dominated by the feudal castle of the Trencavel family.  It was built on the Roman wall in the early 12th century.  The watchtower was raised and the defences were strengthened with crenelations before the crusades against the Cathars took place.  In 1266, Carcassonne was annexed to the domain of the king of France and in the  13th/14th centuries, the fortress was was transformed into a lordly residence.

I particularly like the wooden hording at the top of the castle walls, because I had not seen anything like them before.   The hording is built overhanging the castle wall to strengthen the defence of the castle in times of siege.  Due to its design it was possible to shoot vertically downwards from it.  These hoardings were widely used in the 12th and 13th century, but they later replaced by stone machicolations which posed less danger from fire.