Prehistoric settlement
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. The settlements remained small until about 4500 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 third 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. At the beginning of the Early Bronze Age (around 2300 BC) the last stelae were erected.
The early settlements have been well documented. There are huts from the middle Neolithic period found near Le Petit Chasseur and under Ritz Avenue. Late Neolithic sites have been found at Bramois and the early Early Bronze Age site is at Le Petit Chasseur. The Middle Bronze Age, however, is poorly documented. From the subsequent epochs, the great necropolis of Don Bosco (the "aristocrat" tumulus of the Late Bronze Age and Iron Age) and the necropolis of Sous-le-Scex from the La T�ne culture.
Celtic and Roman town
At the end of the first century BC, Sion was the capital of the Seduni, one of the four Celtic tribes of the Valais. Julius Caesar mentions them asNantuates Sednnos Veragrosqne
