Rudenz Castle, Medieval tower in Flüelen, Switzerland.

Rudenz Castle is a fortified tower near the centre of Flüelen, with a rectangular floor plan of 11.5 by 14 metres. Its walls are unevenly thick: 2.5 metres on the east side and 1.8 metres on the other three. The tower is topped by a four-gabled roof with an onion dome spire, and a wrap-around balcony and new windows were added in the 18th century. Inside are eleven rooms, a great hall, a large kitchen and cellars.

The tower was built in the early 13th century to guard the Gotthard road and house an Imperial customs post; around 1300 the customs right belonged to the Lords of Attinghausen. The tower is first mentioned in 1369, with Baron Johann von Attinghausen as first known owner. Through marriage around 1360 it passed to the Knights of Rudenz from the Haslital; Johann von Rudenz, last of his line, died in 1382.

The castle's name comes from the Knights of Rudenz of the Haslital, who acquired the tower through marriage around 1360; Johann von Rudenz, last of his line, died before 1383. Since 2005 the municipality has opened the great hall for events and a public park on the grounds, where a children's playground now stands.

The tower stands near the centre of Flüelen, with the Rudenzpark on the castle grounds open to the public and a children's playground installed on the site. The great hall has been opened for events since 2005. Only a low wall remains around the tower, the corner towers and most of the curtain wall having been demolished.

The tower's walls are not evenly thick: the eastern wall measures 2.5 metres, the other three 1.8 metres. The 11.5 by 14 metre rectangular plan and the remains of the filled-in dry moat show how the customs post was built to face the Gotthard road.