About 10km south of the city centre, Schloss Benrath is a park-and-palace ensemble where elector Carl Theodor, a man of deep pockets and good taste, came to relax and frolic in the late 18th century. Designed by Frenchman Nicolas de Pigage, the three-winged palace centres on the residential tract (Corps de Logis), where tours offer a glimpse of the elector’s lifestyle. Tours in English run at 3pm Tuesday to Sunday; tours in German are more frequent.
The other wings contain an old-school natural history museum and a museum of European garden history that may well grow on you. The day pass includes the Corps de Logis as well as access to the park and the two museums. If you don't want to see everything, separate tickets are available as well.
