In the architectural landscape of Sardinian Romanesque architecture, the repertoire of plants includes first of all the type of church with a longitudinal structure, with a semicircular apse to the east. The most important cathedrals and churches have three naves, divided by arches on columns or pillars. The capitals are sometimes examples of marble from the Roman age, for reuse.
The naves can have wooden roofs or stone vaults. They were made barrel vaults, with or without grooves, or by cross. Several churches, especially in the 12th century, had a mixed roof system: wooden ceiling in the central aisle and barrel or cross vaulted on the sides. The outer roofs are almost always tiled.
Another type of plan is the one with two naves, both with apses, used for a group of 12th-13th century buildings, often with barrel vaults. Most of the Romanesque churches in Sardinia, especially the smaller ones, however, have a single aisle plan, mainly covered in wood. In this type of building characterized by simple construction, the barrel bell tower is missing, replaced by the sail one raised on the façade.
Apart from two churches completely built of bricks, the material used is stone, cut into machined blocks and carefully put in place. The availability in local quarries determines the use of sedimentary (limestone, sandstone, tuff) or volcanic (granite, andesite) stone blocks. When it is present in the form of columns or sculpted capitals, white marble is always the result of reuse. In fact, the island lacks white marble quarries exploited in ancient times and capable of providing materials in quantities useful for mining for construction purposes.
A chronological distinction characterizes the judicial churches. It is possible to identify an initial Romanesque period, which can be placed between 1050 and 1150 and characterized by the presence of workers who come from Pisa, accompanied by those from Lucca (as in the church of San Giovanni di Viddalba) and by the Catalan and Provençal ones who arrived following the monks of the abbey of San Vittore in Marseille (San Saturnino in Cagliari, Sant'Efisio di Nora near Pula).
During this period, large buildings were built and there was a tendency to favor the structural aspect over the decorative one. The most significant buildings of the period are San Gavino di Porto Torres, Santa Maria del Regno di Ardara, Santa Maria di Bonarcado and the cathedrals of S. Simplicio di Olbia, Santa Giusta and Sant'Antioco di Bisarcio (Ozieri).
This period of experimentation was followed by that of mature Romanesque, between 1150 and 1250, in which a deeper connection with Pisa was expressed, guaranteed by the circulation of workers between the island and the mainland, and by the massive presence of merchants who played an important role in the economic and political fields.
Starting from the church of San Nicola di Ottana, a building that mediates between the two moments, the application of new solutions is recorded, with the creation of grandiose buildings in which the trend towards architectural decoration finds more and more space. More evident in the facades, the new decorative system involves the creation of false overlapping loggias, which find their most complete expression in San Pietro di Sorres. From 1160, another innovation intervened, with the diffusion of the bichrome work, consisting of the alternation of rows of dark stone (volcanic in different shades) and light stone (calcareous). The best known and most significant examples of this technique are the Holy Trinity of Sacchargia, Santa Maria di Tergu and San Pietro del Cruciisso in Bulzi.
A third phase is that of the late Romanesque period, between 1250 and 1300, characterized by the insertion of Gothic decorative elements in a still Romanesque structure. This is justified by the fact that in Sardinia the advent of Gothic did not radically change the methods of construction, but was inserted into the Romanesque cultural fabric in continuity with it. At an early stage, the changes mainly affected surface elements, such as the shapes of hanging arches or windows or legs, which took on a more elongated appearance.
The expansion of the Santa Maria di Bonarcado is representative of this last phase, which can also be seen in the reconstruction of the cathedral of San Pantaleo di Dolianova, in San Pietro di Zuri (Ghilarza), in whose factory the master Anselmo da Como worked, and in the church of San Pietro Extra Muros in Bosa, where the presence of Anselm himself and his workers can be identified.