The topography of Sion is particular: located in the middle of the Rhone Valley, the city of Sion is dotted with hills. They have always been occupied by men who have made them places of observation and defensive sites.
In Sion, four castles are worth visiting. The two most remarkable Sedun fortifications stand on the twin hills of Valère and Tourbillon. On the top of the hill of Tourbillon, the highest, a castle was erected around 1300 by the Bishop of Sion to make it his residence. The other hill is home to the fortified town surrounding the Basilica of Valère.
Below these two hills, the castles of Majorie and Vidomnat, whose construction dates back to the 12/13th centuries, are today occupied by the Valais Art Museum.
Facing them, at the other end of the city of Sion, stands the hill of Montorge. There are also ruins, vestiges of the castle burned down in 1417 and never rebuilt since then.