The remains of the Castle can be visited
Bishop's Castle

The Episcopal Castle in Bruchsal, also known as Alte Burg, is a structure in the Karlsruhe district, Baden-Württemberg. Of the original complex, only the keep remains visible today, considered the oldest building in the city.
History+
Archaeological findings indicate that parts of the castle already existed in the 11th century. Its first documented mention occurred at the end of the 12th century. Between 1178 and 1189, Speyer Bishop Ulrich II von Rechberg had the castle built or expanded using his private funds. He bequeathed the complex, consisting of a defensive tower and a surrounding wall, to the Diocese of Speyer in 1190. In the early 14th century, Bruchsal was the scene of military conflicts, prompting Bishop Gerhard von Ehrenberg to expand the castle in 1358.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://commons.wikimedia.org/wiki/File:Bruchsal_Bergfried_1983.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: 49.1248, 8.5990