Burg Dub, Medieval castle ruins in Tasov, Czech Republic

Burg Dub, also called Tassenberg, is an early Gothic spur castle ruin on a wooded promontory above the Oslava, 1.5 km southwest of Tasov. Its five-sided core measures 55 by 30 m, enclosed by walls nearly 2 m thick; a triangular outer bailey and a rock-cut moat 19 m wide and over 5 m deep survive.

The castle, originally called Tassenberg, was founded in the 13th century by the Tasov family, possibly Vznata (mentioned 1268) or Tas (using the title in 1292). First documented in 1334, it was divided in 1366 and likely destroyed during the Moravian fratricidal war. By 1550 it was recorded as the deserted castle Duby.

The castle ruins represent an example of early Gothic fortification architecture and maintain protected status as a Czech Republic cultural monument.

The ruin stands on private land and is not open to the public, so it cannot be visited. It lies 1.5 km southwest of Tasov above the Radkovský Mill on the left bank of the Oslava, opposite the mouth of the Kameňák stream.

The complex features a distinctive pentagonal layout with a separate outer fortified area, separated from the main structure by a significant moat. This careful defensive design reveals how medieval builders thought about protection.