In Salzberg, Austria, just under the surface of Hochkogel Mountain, is the largest known ice cave in the world, stretching 26 miles into the heart of the mountain.
A mile of the cave is open to the public, and about 200,000 visitors flock to Eisriesenwelt each year. The lucky visitors get to see frosted formations, icy spires, frozen tunnels and frozen waterfalls. Some of the sights have been frozen in time for hundreds of years. Check out some cool pics of the cave below.