The princely collections are installed in a building on the Karlsplatz. The exhibitions on geology, paleontology, mineralogy and zoology on the ground floor are displayed in period furniture (1868). A picture gallery on the second floor has works..

A monumental fountain in the middle of the castle gardens (Donauquelle) marks the place of what is considered to be the official source of the Danube. The river flows for nearly 2 850km before it reaches the Black Sea.