The Castello Visconteo served as the seat of the Visconti Dukes of Milan from 1513 to 1798. It is now an archaeological museum, housing Locarnese artefacts from the late Bronze Age to the High Middle Ages. https://www.myswitzerland.com/en-in/near/near-summer/excursions-summer/excursion-summer/historical-switzerland/castles-palaces/the-castle-of-locarno.html