This castle, set just beyond the lake's edge and reached by a causeway, is believed to have been built on the ruins of a Roman fortress. It dates from 909 or earlier (although it was rebuilt in the 17th century after a fire) and has a picturesque courtyard, a late-Gothic external staircase and sgraffito from 1578. Flanking the lake on the eastern side and forming a backdrop for the castle is a pretty nature reserve known as Toscana Park.