The city is famous for the Cité de Carcassonne , a medieval fortress restored by the theorist and architect Eugène Viollet-le-Duc in 1853 and added to the UNESCO list of World Heritage Sites in 1997 .
This bastide , which was thoroughly restored from 1853 by the theorist and architect Eugène Viollet-le-Duc , was added to the UNESCO list of World Heritage Sites in 1997 .