High above Lake Baldeney in the Stadtwald district of the city, the remains of the medieval Isenburg castle rise up on a rocky outcrop. 750 years ago, it was one of the largest and most important fortresses in the region and it dominated the area around Essen. The ruins fell into disrepair over the years and became overgrown by forest. It was not until about 70 years ago that the larger parts were excavated and made accessible.

The entire castle site is now a listed monument and belongs to the city of Essen. In September 2002, a historical experience trail was opened on the castle site, which provides visitors with details of the history and life of the castle and its inhabitants on six information boards. Funding was provided by the Stiftung zur Verschönerung der Stadt Essen (Foundation for the Improvement of the City of Essen).