Ronsecco is home to two castles built under the lordship of the Bordonni family: one, dating back to the 13th or 14th century, of which almost nothing remains, and a second, dating to the late 14th or early 15th century, which is still visible in the town’s historic center. Square in plan, it was the scene of violent clashes in the 15th century between the House of Savoy and Galeazzo Maria Sforza.