Castello di Pedres, Medieval castle on granite hill in Olbia, Italy.

Castello di Pedres is a medieval granite castle on a hilltop at the edge of Olbia, made up of the remains of four towers and two courtyards enclosed by polygonal walls. Stone staircases connect the different parts of the structure, giving a clear sense of how the defensive layout was organized.

The castle was built in the late 13th and early 14th centuries during a period of Pisan and Aragonese influence, and it was meant to protect the nearby city of Civita. Over time it lost its military role and gradually fell into the state of ruin that visitors see today.

The castle's name comes from the granite, pedres in Sardinian, of the hill it stands on, and the ruins are one of the symbols of Olbia and of the Judicate of Gallura. The single surviving tower, 89 metres high, still lets visitors see the whole plain of Olbia down to the sea.

The hill is reachable on foot from Olbia, but the path is steep and the ground is uneven, so sturdy footwear is a good idea. The ruins are fully exposed to the elements, which makes a visit on a cooler or overcast day more comfortable.

The keep originally had four floors, and its only entrance was about 6 metres above the ground, reached by retractable wooden ladders that were pulled up in case of attack. From the top, the whole plain of Olbia and the sea were visible. After World War II the ruined castle was used as a functional structure for managing the nearby Olbia-Venafiorita airport.