The sacred well of Milis testifies to the Nuragic presence in the territory of Golfo Aranci. Located near the railway station, it was discovered in 1883. Constructed of finely worked shale and limestone ashlars, it has a staircase facing southeast, leading to the well chamber with a tholos structure and an internal limestone basin, still fed by a natural spring. Of the original 40 steps, 22 emerge today. The roof is formed by lintels sloping inversely to the staircase. In 1884, Pietro Tamponi found nearby a gold ring weighing about 10 grams; in 1937, during excavations directed by Doro Levi, Francesco Soldati discovered three bronze objects: a small dagger with two holes and pegs, a cord bracelet, and an Italic arched fibula. Used until a few decades ago as a railroad cistern, the monument will soon be open to visitors after a recent restoration.