It is divided into the fortified Cité de Carcassonne and the more expansive lower city, the ville basse. Carcassone was founded by the Visigoths in the fifth century, though the Romans had fortified the settlement earlier. The fortress, which was thoroughly restored in 1853 by the theorist and architect Eugène Viollet-le-Duc, was added to the UNESCO list of World Heritage Sites in 1997.