The Dome's official name is "Cattedrale di Santa Maria Assunta". It is situated in the historic center of Oristano as part of a Byzantine settlement.
This has been confirmed by the discovery of graves in the churchyard. It was rebuilt in Romanesque style around 1130. Of the early Byzantine church
there still are remains visible in the garden. The Romanesque church was probably destroyed during a siege around 1195 but it was (at least partially)
restored in the thirteenth century during the government of Mariano II (see the inscriptions on the door knockers). During the eighteenth century the
entire building was rebuilt, except for three chapels of the transept.