The Church of San Leonardo, which gives its name to the hill, is located a few meters west of the military installations of the Castle of Balaiana.
The Church of San Leonardo served as the chapel of Balaiana Castle and is one of the smallest Romanesque buildings on the island. The reasons for the interest lie in the organic and spectacular integration into the Gallura landscape and in the building material granite, which was only used in a few Romanesque churches in north-eastern Sardinia between the 11th and 13th centuries.
The construction dates back to the 12th century. The architectural structure is very simple: hall with a single barrel-vaulted nave, semi-circular apse on which the basin rests. The entrance is on one of the sides of the church, the south side, and is accompanied by a very narrow window; Another window is perfectly aligned in the center of the apse, while there is a cruciform opening in the upper part of the W facade. A low wall protects the W side of the building which is all granite with slate gable panels. The construction technique consists of a series of horizontal rows of blocks, smaller than those used for the castle and less finished.