Mühlsteinhöhle, Cave in the Vulkaneifel, Rhineland-Palatinate, Germany

Mühlsteinhöhle is an artificial cave on the summit of the Nerother Kopf, east of Neroth, just below the Freudenkoppe castle ruin at about 640 m. It is 18 m deep with a vault up to ten metres high, cut into a vertical lava wall. Unfinished millstone blanks remain on the walls, and broken millstones lie outside.

The start of millstone quarrying at Nerother Kopf is unknown but likely predates the castle built around 1340. Stones were cut from the lava cliff with hammer and chisel and finished on site; unfinished blanks remain on the cave walls. Quarrying resumed in later periods, with the last evidence dated 1788. On 31 December 1919, members of the Wandervogel founded the Nerother Wandervogel in the cave.

The cave's name comes from the millstones cut here; unfinished blanks still stand in its walls, and broken pieces lie outside. A local legend, recorded in the verse "Op dem Nerother Kopp", says the cave was part of an underground passage to other castles. On 31 December 1919, members of the Wandervogel founded the Nerother Wandervogel inside the cave.

The cave lies just below the Freudenkoppe castle ruin at about 640 m, reached on foot via a hiking trail; the entrance is not accessible by car. The cave is 18 m deep with a vault up to ten metres high, and it has no lighting, so bring a torch.

On 31 December 1919, members of the Wandervogel youth movement met inside the cave to found the Nerother Wandervogel. A local legend, recorded in the poem "Op dem Nerother Kopp", claims the cave was part of an underground passage linking the castles, though a collapse of earth later blocked a side exit.