In the Munster area of Germany there are more than 100 moated castles still surviving.  One such castle is the medieval fortress of Burg Vischering, near Ludinghausen.   Still owned by the same family that built it in 1271, the Counts Droste zu Vischering, it is just what one would expect of a medieval castle:  well fortified, impregnable, and not very hospitable.  The unique semi-circular stronghold has walls and parapets five feet thick, a tower in the central courtyard and a wide, deep moat that protects it.  More than most other castles in this area, Burg Vischering provides a vivid impression of how well-fortied such buildings were.  It remained unconquered for centuries.