The Borromean Fortress at Arona is a defensive construction built about the year 1000 A.D. under Longobard domination; it overlooks the waters of Lake Maggiore and together with the Borromean Fortress of Angera, its opposite  and “twin”, it was one of the main strategic control points of Lake Maggiore.

Destined purely for defensive purposes, in the following centuries, the fortress passed under the control of the bishops until, by about the 11th-12th centuries, it had the role of a simple refuge. For four centuries, the Fortress was in the hands of the Borromeo Family, being the birthplace of the future Cardinal Saint Charles Boirromeo in 1538.

The history of the Fortress of Arona reaches its conclusion in 1800 when Napoleon’s army received orders to destroy the fortifications occupied by the Austrians; since then, only a few remains are left of the three fortified walls, the donjon, the Romanesque oratory of St. Ambrose, the Arms Room and the room where St. Charles Borromeo was born on the 2nd October, 1538.