The Castle can be visited
Museum
Steinau Castle

In Steinau an der Straße, Steinau Castle stands as an example of early Renaissance architecture in Hesse. Originally a medieval castle, it developed into one of the largest and best-preserved castle complexes of this era and once served as a secondary residence for the Lords and Counts of Hanau.
History+
The castle's origins lie in a medieval fortress, whose exact appearance is unknown but may trace back to a foundation by Fulda Abbey. By the late 13th century, the castle was in the possession of the Counts of Rieneck before passing to the Lords of Hanau as a dowry through the marriage of Ulrich I of Hanau to Elisabeth of Rieneck. Steinau Castle was used as a dower residence for countesses.
Source: Wikipedia · Licence: CC BY-SA 4.0
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: 50.3119, 9.4611