The medieval ruins of the Castrum of Castelseprio were named a World Heritage Site by UNESCO in 2011 as part of the project entitled "Italia Longobardorum – Longobards in Italy. Places of the Power (568-774 A.D.)" which includes a number of places linked to the passage of Lombard civilization in the area.

The Castrum of Castelseprio in particular was built on a road linking Novara to Como at the top of a hill protected by a thick wall, with towers that appear every 30 metres. The castrum performed a military function until the 13th century, to be inevitably abandoned years later.

Significant examples of military architecture can still be seen in the Castrum of Castelseprio today, also including the complex of Torba, Santa Maria Foris Portas and the church of San Giovanni. All of these buildings are important examples of the Lombard period, object of study as well as other artefacts from the castrum.

Numerous civil buildings have been discovered on the site along with numerous tombs. One tomb with its Lombard burial treasures was discovered inside the walls of the church of San Giovanni, in addition to others along the sides of the church.