The artificial dripstone cave with its lake and waterfall was modelled on the Hörselberg from the first act of the Wagner opera "Tannhäuser".

This natural stage, built in 1876/77 by the landscape sculptor A. Dirigl, was lit by arc lights. The electricity for this was generated by 24 dynamos in the machine house 100 m away, one of the first electricity works in Bavaria.

The grotto features a "royal seat", a Lorelei rock and a gilt boat in the shape of a shell.