In the highest place, on the hill of La Terra, where the new city’s life had begun, a first place of worship was built during the Lombard period, already existing in 969 when the archdiocese of Avellino was established.

Becoming two small, the first church of Santa Maria was demolished to leave the space to the actual Cathedral, built between 1132 and 1166. Originally in romanesque style, the cathedral was built since the beginning dedicated to the Assunta. The geological events of the city made it obligatory over the centuries veto recover and restore the structures, which, however, maintained the characteristics of the romanesque until the Seventeenth century when the first changes happened according to the new architectural and artistic trends. The Eighteenth-century interventions definitively changed the Cathedral appearance, making it a baroque monument, as well as strengthening the foundations in 1709. Works which, together with the ones made in the Twentieth century after the war, made it possible to avoid disastrous consequences from the earthquake of 1980. Instead, the façade was rebuilt in 1857 on a design by the architect Pasquale Cordola and built with marbles decorated in neoclassical style, with three entrance portals and the statues of the patron saint of the city, San Modestinoda Antiochia, and the patron saint of Irpinia, San Guglielmo da Vercelli. The bell tower with a square plan has a stone base from the Roman period of the 1st century BC, coming from Abellinum and has a characteristic onion dome.

The Latin cross interior is divided into three naves with ten chapels; the coffered ceiling with gilded wood is adorned with a large canvas dedicated to Maria Assunta in cielo (Mary of the Assumption), by Michele Ricciardi in the first decade of the Eighteenth century. The arches between the naves and the domes which give light to the side aisles were painted by Achille Iovine. Of the numerous art works exhibited in the mother church of Avellino, the most important painting is located in the Chapel of the Magi: the Adoration of the Magi from the end of the Sixteenth century by Marco Pino da Siena, even if recently it has been hypothesized that it is attributed to Ippolito Borghese. Also in the right aisle, the Chapel of the Crucifixion opens, which houses the relic of a Holy Thorn from Jesus crown and a fragment of the Cross donated by Charles of Anjou and coming from the Royal Cathedral of Paris, protected by a precious reliquary in the shape of the cross by Biagio Guariniello. You can also admire the Crucifixion of Jesus. In right aisle, the Chapel of the Assumption houses the venerated wooden statue of the Immaculate Conception, which is carried in procession every 15th of August, a masterpiece by Nicolò Fumo. In the left apse of the presbytery, there is the Chapel of the Treasure of San Modestino, the most important, which houses the relics of the Saint (to whom the Cathedral is also dedicated) and of Saints Flaviano and Fiorentino, solemnly tranferred to Avellino on 10th of June 1166. The chapel was built after the earthquake of the 1688 on a project by Giovan Battista Nauclerio, who used the best Neapolitan craftsmen of the time for the rich wooden decorations and precious marble and for artistic glass windows. The silver bust of San Modestino by Biagio Guariniello is of great value. In the apse the magnificent Sixteenth-century wooden choir is remarkable; the main altar is from the Eighteenth century and replaces a previous one, perhaps by Fanzago; the vault is frescoed with three episodes from San Modestino’s life by Achille Iovine.

From the transept of the cathedral, you can access the space below the central nave, where the church of Santa Maria dei Sette Dolori is located, known as the Crypt of the Addolorata. It is the most ancient part of the entire Duomo complex and keeps the original romanesque style. White columns with early christian capitals separate the three naves. On the vaults, there are the paintings by Michele Ricciardi. From the crypt, where some Bishops of Avellino are buried, you go down into the Lombard tunnels.