Schloßberghöhlen is Europe's largest sandstone caves…read more As part of the Hohensalzburg Castle - we were advised there are something like 10-12 levels that were once used primarily for defense. During World War II the townsfolk used the caves for protection against air raids. In more modern times, the caves were used as banquet halls and for raves.......recognizing the potential hazard to the structural walls ( as they are only sandstone & one can scrape sediment away w/ one's fingers ) the site was closed off and is currently being turned into an educational / tourist destination Layers of mineral deposits show where this was once all underwater from the swirls in the pattern of red & tan layers They prefer guided tours - hardhats are issued at check in & you can reserve tour guides who speak a variety of languages We walked around the 1 level they currently have open - there are large buttons along the way which will light up parts of the cave & showcase various points of interest. We saw roots from trees on top of the mountain we were currently under; the "Throne Room" with its huge, cavernous rotunda; and a banquet hall that still had a large wooden table in it - must have been where they held their events. Overall, a nice excursion & if you're in the area, worth a visit