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. The show-piece is the collection of Roman glasses excavated in Ticino. An extensive collection of approx. 200 exhibits. Documents on the Locarno Peace Talks (Locarno Pact, 1925) are to be found in the municipal museum.