Attracting 500,000 visitors per year, Luray Caverns is a godsend for caving enthusiasts - showcasing a fascinating alien world filled with beautiful limestone structures and mirrored pools.

Stalactites and a stalagmites are seen on August 11, 2012 in Luray Caverns in Luray, Viriginia. The stalactite is above, and hangs downward like an icicle while the stalagmite is below and sticks up. They grow in pairs, the slightly acidic water dissolves some of the limestone, carrying it downward. When the water evaporates, the limestone appears to have flowed downward. Some of the water does not evaporate until it has fallen through the air, and landed on the floor, the remaining limestone and minerals build the stalagmite. Often, the stalactite and stalagmite will connect, and become a column. AFP PHOTO/Karen BLEIER