Set in the gentle landscape of northern Campidano plain, it is the town of gates: dozens of various architectural value can be seen in the town centre. Simala a small town with 350 inhabitants in Upper Marmilla. Founded in a fertile valley crossed by Rio Mannu and cultivated for cereals, legumes, fruit, grapes and olives. The river, once called the ‘sacred river’, flows through cane thickets and groves of poplars and willows in a sacred pre-Nuragic area with a menhir related to the water cult in its centre. It is the most important Neolithic site in an area at the foot of Monte Arci Park and its deposits of obsidian, the Prehistoric ‘black gold’ of the Mediterranean. Numerous Bronze Age sites are in the area: the Giant’s Tomb of Piscina Craba and about a dozen nuraghes. Following Roman conquest, the area was densely populated and mined for lead and silver. Evidence of many settlements and traces of a road connecting Neapolis to Uselis are still visible. The most important Roman site is the Rustic Villa of Gemussi, equipped with thermal baths embellished with mosaics and other decorations. The Paleo-Christian Cemetery of Santu Sadurru is also of note.