The church of San Nicola, built before 1160 in Ottana, stands as a remarkable example of Romanesque-Pisan architecture in Sardinia. The building, made of valuable basalt and trachyte ashlars, stands out for its rich and refined architectural decoration. The façade, divided into three orders, features a series of ornamental pilasters in the first and second orders that form three elegant double-framed arcades, embellished with sophisticated rhomboid motifs. The second order is further enriched by the presence of a finely worked double lancet window. The gable, an element of particular interest, is characterised by five arches containing ceramic architectural elements, an unusual feature that deserves in-depth archaeological and historical study. The northern façade is adorned with a series of small hanging arches, a typical element of the Romanesque style that gives the building an elegant visual rhythm.
Inside the church is the 'Ottana Altarpiece', a 14th-century polyptych of the Tuscan school of extraordinary artistic and historical value. Prominent among the characters depicted is the figure of Mariano IV d'Arborea, a crucial protagonist in the medieval history of Sardinia. The presence of this work of art underlines the significant role the church played in the historical and political context of the time.
The church of San Nicola was the seat of the Ottana diocese until the 16th century, a circumstance that explains the sumptuousness of its decoration and its historical relevance. This building thus represents not only an eminent example of Romanesque architecture in Sardinia, but also tangible evidence of the complex political and religious dynamics that characterised the island in the medieval period.