Carcasonne is a medieval, town in southern France. The city has two parts, La Cité and La Bastide St. Louis. It is the largest fortified city in Europe. La Cité is the part of the city that is in fortifications. Construction on the La Cité part of the city began in 1120 during the Crusades. The impregnable fortification features 52 towers, gatehouses, two rings of ramparts, and over three kilometers of battlements. The fortress fell into in the 17th, 18th, and 19th when it lost its military significance, but was by theorist and Eugène Viollet-le-Duc in 1853. Today, the parts of the walls are home to shops, restaurants and hotels. There are even 120 people who live the walls. The fortress was named a UNESCO world Heritage site in 1997.