The first record of a church dedicated to “Sanctu Nicola de Thatari” is found in the Condaghe di San Pietro di Silki dating from the early 12th century.
After the mid-13th century a Romanesque-Pisan style temple was built, of which the lower part of the bell tower and a section of wall in the Aragonese sacristy remain.
The canonical transfer of the metropolitan see from Turris to Sassari, which legally took place in 1441, posed the problem of a new cathedral. The rebuilding project did not go ahead until 1480. The Romanesque building, of which only the bell tower remains, was demolished almost in its entirety, and the present one in Catalan Gothic style was built in its place. The complex is raised on a single-nave plan and divided into two major and one minor bay. At the junction with the transept rises the dome. In the back of the altar, in a room partly coeval with the construction and partly late (18th cent.), is the choir, a valuable wooden work by Sassaresi cabinetmakers from the second half of the 17th century. Four chapels on each side open along the nave. They originally had cross vaults and were connected with pointed arch openings. The imposing Baroque façade, with its remarkable ornamental impact, was erected early in the 18th century and replaced the Gothic gabled façade with rose window and three openings with pointed arches, one central and two smaller side ones. The complex houses the “Ori, Argenti e Paramenti” section of the Diocesan Museum of Sassari, while inside the church one can admire the 14th-century panel painting of the Madonna and Child, the wooden choir and the neoclassical funeral mausoleum of the Count of Moriana.
