It is a monument of exceptional interest, since it is the only original testimony of the structures in high and shell wells and sacred sources of Nuragic age. Dating back to the XII-X centuries BC, it is built with blocks of trachyte and basalt perfectly square, put in place without the use of mortar, which were brought here from afar through Isalle valley, since the trachyte is not present in this territory. The structure is against the rocks and has typical layout of sacred wells: hallway, staircase and room which collected water from the spring vein, held sacred by Nuraghic populations. The facade, which originally elevated up to 7 meters, has a unique coverage gable ends with an acute triangle pediment, decorated originally with twenty swords votive bronze. Two monolithic arches are inserted in the upper walls. Rectangular vestibule, a staircase with four steps introduces the tiny compartment that collects water, with coverage tholos. On the paved floor a small pit gathers impurities, so that the water in the well keep always clear. Within this environment numerous votive objects were found: stilettos, rings, bracelets, pins, elements of an amber necklace and, of particular value, bronzes representing offerers, warriors and characters with cape and control stick. Outside of the well develops a wall of trachyte, irregularly curved, in which two small niches for the deposition of the offers are present. Near sacred spring it is displaced nuraghe St. Lulla, to whom holy site is closely connected.