The 4.4 km-long Hermannshöhle is one of the largest caves in the Lower Austroalpine Unit. The cave is unusual in two respects: its dense network of corridors is arranged in a three-dimensional maze and the most outstanding macro- and micromorphologic features were caused by paragenesis. The aim of this study was to enlighten the origin of this cave using morphological and sedimentological observations as well as U/Th dating of speleothems. First results show that the palaeo-environment of the Hermannshöhle was drastically different from today. Highly corrosive water sourced from nearby non-karstic gneisses and schists gave rise to well-developed contact karst features. A distinct system of paragenetic canyons developed following pulses of clastic sediment input creating the unique maze character of the cave. Preliminary U/Th results suggest that speleothems from the middle level of the cave are already older than ca. 600 ka.