Accidentally uncovered by copper-shale miners in 1865, this anhydrite cave is one of the largest of its type in Europe. Fifty-minute tours through the 13,000-sq-metre cavern are conducted hourly, taking in shimmering underground lakes, bizarre gypsum ceilings and stone slabs mythically revered as the table and chair of the Emperor Barbarossa, supposedly buried in these hills. Outside, children can let off steam in a 'geo-adventure landscape' while learning about the area's geology.
The caves are 7km west of Bad Frankenhausen, north of Rottleben. Bus 451 runs regularly between thre two towns.