The remains of the Castle can be visited
Alsbach Castle

The Alsbach Castle Ruin, once known as Bickenbach Castle, stands on a hill near Alsbach-Hähnlein in the Darmstadt-Dieburg district of Hesse.
History+
The origins of Alsbach Castle date back to around 1235, when it was built by the Lords of Bickenbach. In the 14th century, it evolved into a co-owned castle with multiple proprietors. Following an attack on Frankfurt merchants by one of the co-owners, Hartmann Ulner von Dieburg, the castle was besieged and burned down by the city of Frankfurt in 1463, but was soon rebuilt. Between 1483 and 1502, Erasmus Schenk von Erbach acquired almost all shares, consolidating ownership.
Source: Wikipedia · Licence: CC BY-SA 4.0 · Image: http://www.wehrbauten.de/thread.php?threadid=971
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: 49.7335, 8.6271