Seen from above, it has a curious inverted 'T' shape, with high steep walls, but this is not its only peculiarity: the southern side has reddish spots and, inside, preserves precious pre-Nuragic and Nuragic legacies, including one of the Tombs of Giants best preserved on the island. The Giara di Siddi, also known as su Pranu, is one of the three basaltic 'tables' of Marmilla that originated following a lava flow that occurred between two and five million years ago. Over time, the atmospheric agents eroded the sandstone rock, while the solidified layers of lava were preserved at a higher level, giving rise, in addition to the Giara di Siddi, to that of Serri and sa Jara Manna (or Giara di Gesturi), the largest of the three, 'home' of the famous little horses.
Rich in many archaeological remains from the Nuragic era, such as the Tomb of the Giants of SA Domu and S'Orku and a protonuraghe on the slopes towards Siddi.
in the southern part there is the sad wreck of a chair lift, a sign of a perverse attempt at tourist development