The remains of the Castle can be visited
Salzwedel Castle

On the northern edge of the old town of the Hanseatic city of Salzwedel, the Salzwedel Castle Ruin, a former lowland castle, rises. Its strategic location at a Jeetze crossing once made it a protective point for a trade route between Magdeburg and Lüneburg.
History+
The castle's origins are presumed to be in the 9th century, where it secured a ford on the Jeetze. Its first documented mention occurred in 1112 when it was besieged by Emperor Henry V. In 1134, the complex came into the possession of the Ascanians when Albert the Bear took it over.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://commons.wikimedia.org/wiki/File:Burg_Salzwedel_Juli_2009.jpg
This description draws on the facts documented in the linked Wikipedia article; Wikipedia content is licensed under CC BY-SA 4.0. Wording and editing: Mobile History.
Location: 52.8516, 11.1514