On 17 January , the former municipality of Bramois merged into the municipality of Sion. Sion has an airfield for civilian and military use, which serves as a base for air rescue missions.
Sion is one of the most important prehistoric sites in Europe. The alluvial fan of the river 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 BC during the late Mesolithic.
The settlements remained small until about BC, during the middle Neolithic, when the number of settlements increased sharply. To support the population increase, farming and grazing spread throughout the valley. They also began burying their dead in Chablandes-type stone burial cists with engraved anthropomorphic stelae. The individual graves changed at the beginning of the 3rd millennium BC in large, dry stone wall communal tombs such as the Dolmen of Le Petit-Chasseur.
During the Beaker culture period in the second half of the third Millennium, dolmens were built once again, but they were smaller and had no podium. Stelae continued to be carved, though these were rich with geometric patterns and sometimes built out of old dolmen. The early settlements have been well documented.
The Middle Bronze Age , however, is poorly documented. The town-hall is said to contain several Roman inscriptions, one of which found at Sion commemorates the Roman presence: Civitas Sedunorum Patrono.
