The Basilica of Sant’Agata Maggiore is located in the city centre, only a few steps away from the Basilica of San Francesco. It is one of the oldest churches in town, as it was erected in the fifth century during the episcopacy of Peter II (494-519 AD) whose monogram is still visible in the nave. The apse was built in the following century during the bishopric of Agnello (556-569 AD) with the contribution of Julianius Argentarius.
The floor of the original church is now approximately 2.50 meters below ground level.

Over time, the church has undergone several changes. In the courtyard that surrounds it (once a graveyard) there was a four-sided porch, replaced in the 16th century by a circular bell tower. In 1688, the mosaics of the apse were destroyed by an earthquake and the floor was then raised by 2.50 meters.

During the restoration works carried out between 1913 and 1918 by Giuseppe Gerola, a prothyrum and a marble mullioned window were added to the façade. The interior is divided into a nave and two aisles. The structure is supported by columns, some of which are topped by Corinthian capitals from the 6th century.
An ancient shrine near the altar of Saint Agatha preserves the ashes of St. Sergius Martyr and Bishop Agnellus. Above, a 1546 painting by Luca Longhi depicts Saint Agatha between Saints Catherine of Alexandria and Cecilia.