In the 12th and 13th centuries, the Isenberg had an ideal location both strategically and in terms of transport. It lay between the capital of the Archbishopric of Cologne (50 km) and the capital of the Duchy of Westphalia, Soest (70 km), exactly on the former Hilinciweg (Little Hellweg, west of the castle) and its crossing over the Ruhr at a ford. However, this ford was not on the old highway between Cologne and Soest. To this day, its name bears witness to the connection to iron, which is literally contained in the Low German Isen. The castle was also the administrative center of the County of Isenberg. At the time of its construction, the Romanesque complex represented an unusually large fortification. The castle consists of the so-called upper and lower castle, each of which is around 120 m long and extends over the ridge of the Isenberg. Today, the castle ruins are a publicly accessible monument. It can be reached from the higher southern side past the moat and keep.
The Isenburg Conservation Association not only maintains the castle complex, but also runs the museum in the Custodis House with research and excavation results on the Isenburg. Other finds are on display in the Iron House in Hattingen's old town. The museum in the castle is open on weekends. Source: Wikipedia)
The Isenburg is definitely worth a hike or a bike trip. If you're cycling, you should be careful not to go to the lower castle, as there are stairs there. With normal bikes, this is certainly not a big obstacle. With heavier bikes, it becomes difficult. I was lucky and a nice gentleman carried my bike for me.