The groups comprise monasteries, church buildings, and fortresses and became UNESCO World Heritage Sites in June 2011 as they testify "to the Lombards' major role in the spiritual and cultural development of Medieval European Christianity".

To the west of the monastic complex is the monumental area consisting of the Capitolium, the republican sanctuary and the Roman theatre, closely linked with the stories about San Salvatore-Santa Giulia.

[4] The Longobards turned the Castelseprio Castrum, which was previously a Roman military outpost and an Ostrogoth defensive bastion, firstly into a place for commerce and then into a monastery (8th century).

A monastery is also a part of the complex, although it had been preserved after being rebuilt in the 13th century, replacing the original Longobard building with another later addition of a quadrangular cloister.

[8] The sanctuary, a testament to the worship of Saint Michael, was the object of the monumental patronage for both of the dukes of Benevento, who both settled in Pavia, which was upgraded with numerous renovations in order to facilitate access to the cave of the first apparition and to accommodate the pilgrims.

The sanctuary has been mostly reconstructed, especially the higher parts; during the Longobard age, only the crypts provided access to the cave where, according to tradition, Michael the archangel had appeared.