The Castle of Carcassonne

Carcassonne is located in the south of France, about 80 kilometres east of Toulouse. Its strategic location between the Atlantic Ocean and the Mediterranean Sea has been known since the neolithic era.
Carcassonne became strategically identified when the Romans fortified the hilltop around 100 BC
The fortified city itself consists essentially of a concentric design of two outer walls with 53 towers and barbicans to prevent attack by siege engines. The walls consist of towers built over quite a long period. One of these towers housed the Catholic Inquisition in the 13th century and is still known as "The Inquisition Tower".
In 1849 the architect Eugène Viollet-le-Duc was commissioned to renovate the whole castle.