This hypogeum;partly dug into the rock;is inside the 17th- century church dedicated to Christ the Saviour in the homonymous village;an important pilgrimage centre.Frequented from the Middle Neolithic age (4th millennium BC);this site has been considered a sacred place by different cultures over the centuries.A sacred well for water cult was dug in the Nuragic age;in the Punic age this area was dedicated to Sid;the healing god;and afterwards the Romans adopted the cult of Asklepius;attributing healing powers to water.Since the 3rd- 4th century AD the hypogeum has been used as a church.The present site dates back to the last Roman period:the plan;with several small rooms;is centred around a spring water well;set in a round domed room with a skylight on the top.In front of it;an apsed room with two skylights keeps another spring water well and a Nuragic baethyl (sacred stone).In almost every wall;Punic;Greek;Latin and Arab inscriptions are still visible together with paintings dating back to different periods;related to pagan and Christian tradition.;Not accessible to disabled people.