The double walls of Carcassonne extend for three kilometers with 52 towers, making them Europe's longest fortifications. The inner wall was built by the Visigoths in the 5th century, then reinforced in the 11th century. The French added the outer wall after taking the city from the Cathars. The walkway on top offers panoramic views of the city, Pyrenees, and Languedoc plain. The space between walls is called the 'lices' where tournaments were held.