In the 1960s, Professor Fritz Eggeling planned a green adventure park with a fairground, football pitches, adventure and water playground for the overgrown and inaccessible site, which still contained the remains of former orchards.

The design was not implemented, however, as the ecological report found that the impact on the natural environment would have been too great.

Reinhard Grebe's green framework plan, which examined the landscape integration of the Hardtberg planning area in the early 1970s, among other things, then secured the landscape structure of the valley, its ecological balance and its function as a valuable fresh air corridor for the Bonn valley basin.

The local recreation area was officially inaugurated on June 16, 1979. The development costs amounted to an impressive 3.3 million marks, and 80,000 new trees and shrubs were planted. The nine-kilometer network of paths opens up large, attractive forest and meadow areas with a variety of seating options. Visitors can easily reach the adjacent recreational areas of Hardtbergwald and Kottenforst on foot or by bike. An allotment site and three reservoirs used by the fishing club complete the leisure facilities for peaceful recreation in the Derle valley. Playgrounds and sports facilities are attached.