The castle ruins once formed a scene in the middle of an artistically designed landscape on all sides of the spa buildings. Today it is a walk-in princely apartment in which time has stood still. Anyone who visits is particularly surprised by the contrast between the outside and the inside.
But this was what the creator and builder of the Wilhelmsbad, the hereditary prince and Hanau Count Wilhelm (1743-1821), wanted: its external design gives the impression of being worn out and decaying. Surrounding the building with oak trees was intended to enhance the effect. The count, on the other hand, had the interior rooms decorated artistically and magnificently. There he withdrew from his obligations in the nearby Hanau residence. This remarkable refuge represents the earliest European example of a pseudo-medieval ruined castle in a landscape garden. One is amazed at the size of the interior. On the second floor level there is a hall that Wilhelm had decorated with grisaille portraits of his ancestors and family members who were living at the time.
Among them is the portrait of his wife, Princess Wilhelmine Karoline of Denmark (1747-1820), whom he cheated on with a mistress in the same rooms. Landscape paintings by the painter Anton Wilhelm Tischbein hang in the bedroom.