An organ located deep within a cave, whose "pipes" are the geological features of the cave itself.

A 300-yard long natural tunnel runs through a ridge deep in the Appalachian Mountains.

A sacred site for Native Americans surveyed by George Washington and owned by both King George III and Thomas Jefferson.

The remains of a failed attempt at medieval nerdery are hidden deep in the woods of Virginia.

Possibly the world's oldest rug, this Egyptian relic is woven entirely from ancient cat hair and once carried a mummified human foot.

This Old Testament garden features 100 plants from biblical times.

Former utopian colony based on the belief that the universe exists in a hollow sphere.

Manatees congregate around a power plant's discharge canal where the water is especially warm.

One-time winter retreats of prolific inventor Thomas Edison and his friend Henry Ford.

An amazing collection of scale model ships.