Sion is the capital of the Swiss canton of Valais. As of December 2009 it had a population of 29,718. Landmarks include the Basilique de Valere and Chateau de Tourbillon. Sion has an airfield for civilian and military use, which, because of its location in a valley, causes a reasonable amount of noise pollution. FC Sion is the local football team. They currently compete in the Swiss Super League.
Sion is one of the most important pre-historic sites in Europe. The alluvial fan of Sionne, the rocky slopes above the river and, to a lesser extent, Valeria and Tourbillon hills have been settled nearly continuously since antiquity. The oldest trace of human settlement comes from 6200 BC during the late Mesolithic. Around 5800 BC early Neolithic farmers from the Mediterranean settled in Sion.