Castello Visconteo, Lowland castle in Locarno, Switzerland

Castello Visconteo is a medieval lowland castle at the edge of the old town of Locarno, in the Swiss canton of Ticino. Only a portion of the original structure still stands, and that remaining section now houses an archaeological museum.

A first castle may have stood here as early as 866; it was taken and destroyed by the Ghibellines in 1260. In 1342 the Visconti of Milan seized the site and strengthened it with massive walls, and from 1439 the Rusca held it as a fief. Swiss forces took it in 1513, and in 1531–1532 large parts of the fortifications were demolished.

The Museo civico e archeologico occupies the castle's surviving residential wings. Its best-known holding is a large collection of Roman glass, shown alongside finds from the Bronze Age and Roman era. Two further sections cover the 1925 Locarno Peace Conference and its treaties, and the city's role in the Reformation, marked in 2017 when Locarno was named a Reformation City of Europe.

The castle sits right in the old town of Locarno and is easy to reach on foot from the main square. Opening hours can be limited outside summer, so it is worth checking before you visit.

The north-east corner holds a bastion built between 1499 and 1512 that may follow a design by Leonardo da Vinci. It is privately owned, and the city's attempt to buy it failed in 2010. The medieval harbour in front of the castle was dredged in 1485 and 1486, silted up, and was abandoned in 1535; its site now lies under a road, with remains visible in the pedestrian underpass.