The sanctuary of Santa Maria is right beside the SS131.
Despite the name, it is a sacred nuragic well. Initially you see a keyhole shaped opening in the ground surrounded by small circular walls. As you get closer you see a set of geometrically pleasing steps. Descending into the darkness you arrive at the bottom of a conical tower and the circular well itself.
Looking up you see a small opening, the sun or moon can be seen through this depending on the season. Astonishing brick work and an air of mystery. Great location for picnic beneath the olive trees.