The complex, which includes the basilica and the adjoining convent of the Friars Minor of the Observance, was built at the behest of St Bernadine of Siena thanks to a donation made by the noble Avogadro family of Zanano in 1442. The interior of the building, which was consecrated on 29 September 1513, consists of a single large nave and three identical chapels on the left; the presbytery has an extensive fresco decoration that descends from the vaults to the walls. One of the most impressive frescoes is the central lunette with the Madonna of the Angels, dated 1502. There was once a large polyptych by Moretto behind the high altar, which was subsequently dismembered between the Pinacoteca of Brera and the Louvre Museum during the Napoleonic suppressions. Other noteworthy interior works include paintings dating back to the first half of the 16th century and the large 18th-century canvas by Pompeo Ghitti depicting the Virgin, Child and Saints Domenic and Catherine of Siena. Since 2008, the marvellous complex has housed the offices of the Cultural and Environmental Heritage System of the Valle Trompia Mountain Community. There is also a privately-owned portion and the cenacle hall used as a conference and meeting room. Despite the modern interventions, the beautiful 15th-century cloister helps to keep alive the memory of the ancient origins of the convent.
The Convent of Santa Maria Degli Angeli is also home to the Ecomuseum of Valle Trompia – The Mountain and Industry and is one of the stages of the Sacred and Art Route.