An architectural complex of considerable historical and archaeological interest, comprising structures from different eras. The bell tower, the most recent element of the complex, dates back to the late 16th century. Adjacent to it are the remains of a Romanesque cathedral, the construction of which was begun around 1090 to serve the diocese of Galtellum (Galtellì). This ambitious project remained unfinished, with only the north side, the transept and an apse realised, offering an interesting testimony of medieval building techniques. The oldest core of the complex is a small medieval church, later enlarged to three naves. This structure preserves recently restored 13th-century frescoes attributed to artists from Umbria and Lazio. The pictorial cycle, depicting biblical scenes, constitutes an important example of medieval sacred art in Sardinia. The stratification of styles and epochs at this site offers a unique overview of the evolution of religious architecture on the island, from the Romanesque to the late Middle Ages, highlighting the importance of Galtellì as a spiritual and cultural centre in the medieval period.