The Imperial Palace at Gelnhausen, in German also called the Kaiserpfalz Gelnhausen, Pfalz Gelnhausen or Barbarossaburg, is located on the Kinzig river, in the town of Gelnhausen, Hesse, Germany.
It was founded in 1170, and like the town whose creation was closely linked to the palace, goes back to Emperor Frederick I. The palace enabled the expansion of imperial territory along an important long-distance highway, the Via Regia.
Wikipedia https://en.wikipedia.org/wiki/Imperial_Palace,_Gelnhausen
Address 12 Burgstraße, Gelnhausen 63571, Germany
Coordinates 50°12'0.167" N 9°11'43.827" E