The top of the Su Muru Mannu hill, that dominates the north of Tharros, was a natural fortification towards the inland areas (figs. 1-2) and this is why it was chosen for the building of fortifications from the Punic Era onwards.

Fig. 1 - Tharros and the top of Su Muru Mannu (from Google Earth. Review C. Tronchetti)

Fig. 2 - Details of the direction of the fortifications on Su Muru Mannu fortress (photo by Unicity S.p.A. Review C. Tronchetti)

The fortifications were changed and transformed over the years, and this makes their interpretation difficult and not yet clear. We can say that they were built in the Punic Era, during the 4th century B.C., but their current aspect is one due to a final Roman renovation, which took part in the 2nd century B.C. The fortifications included a drystone inner wall (C), built from rough basalt blocks , with the insertion of smooth sandstone blocks as decoration. A counterpoised counterscarp wall (B) in basalt blocks, that supports a strong agger in the ground, and forms a wide moat (A) (figs. 3-6).

Fig. 3 - The fortifications: A) the moat; B) the counterscarp wall; C) the perimeter wall (photo by Unicity S.p.A... Review C. Tronchetti)

Fig. 4 - The basalt perimeter wall with smooth sandstone blocks (photo by Unicity S.p.A.)

Fig. 5 - The counterscarp wall (photo by Unicity S.p.A.)

There is a postern in the perimeter wall, that was later blocked, built from square, light sandstone blocks (fig. 6). The top part of the wall has collapsed, but we can reconstruct it as having arched merlons (fig. 7).

Fig. 6 - The postern (photo by Unicity S.p.A.)

Fig. 7 - A merlon on the perimeter wall (photo by Unicity S.p.A.)

During the 1st century B.C., the moat was no longer considered functional and was partly filled in; a few years later it was used as a small necropolis.