Wilhelmsthal park is located far away from the hustle and bustle of the city in Calden and offers recreation in a fairytale-like ambience. Schloss Wilhelmsthal castle and its gardens with elaborately planted borders regularly provide the backdrop for popular open-air events such as the "Gartenfest Kassel" festival.

William VIII commissioned the construction of the rococo-style Schloss Wilhelmsthal castle from 1743 onwards as a pleasure palace and hunting lodge. Rather unusually, it is situated at the park's lowest point. The rococo gardens were never completely finished. An impressive grotto structure with water features that dates back to this era survives. Landgrave William IX had the park remodelled into a landscape garden. The artificial ruin of a mediaeval hilltop tower, the Wartturm, also dates back to this time. It affords fantastic views across the surrounding countryside.