Romanesque in origin, the church is thought to have been built over a Roman temple in the time of Bishop Idacio. The first historical reference to the church dates from 1259, with the tower and porch from this period still standing. It was restored during the reign of João III (in the sixteenth century), based on Renaissance models from the time, and then underwent new reforms in the eighteenth century. Its interior contains three naves, supported by thick columns covered with a roof made of chestnut wood.

A dome covers the main altar, and a lantern stands over the Chapel of the Most Holy. In a small square to one side of the church is a pelourinho or pillory in Manueline style, where justice was administered in mediaeval times.

It was during the Roman period, one of the most important urban centers of the peninsula, and the records of the time of suevas invasions, said the city as the seat of a Christian bishopric. The existing temple would have been partially destroyed, having the time of Arab occupation, saying the extinction of the diocese.

The documentary references to the Church of Santa Maria Maggiore appear fixed in the Inquiries Afonsinas of 1259. The Romanesque temple have possibly been built in the twelfth century, on another of Visigothic origin. Still standing bell tower and its portal of the medieval structure.

A major renovation were made to the temple during the reign of King John III, to integrate the Romanesque structure, two portals and the Renaissance style.

Lines clearly inspired by Italian architecture, with a perfect arch and flanked by small columns is inserted into the triangular pediment shot.

The lateral portal, is assigned to the mason, sculptor John Noble. The decor is full of grutesco reasons, having carved in the upper surface of the arch busts of St. Paul and St. Peter.

In keeps it inside the medieval structure composed of three naves marked by robust pillars, wooden ceiling (XIX century), originally the cover was made by cannon vaults. Before the chapel, there are two chapels. The Chapel of the Blessed Sacrament of the century. XVI and rebuilt in the mid-eighteenth century. In the front room, the chapel is dedicated to Santa Maria, behind which lies the sacristy.

The chancel was rebuilt in the second half of the sixteenth century (1561). Opens with a pointed triumphal arch, surmounted by a panel of tiles, alluding to the Assumption of Mary.