The mysterious wonder of an underground waterfall is illuminated by multicolored lights.

This historic "City of the Dead" lies prominently in the center of New Orleans' famous Garden District.

The world's longest known cave system.

A beautiful geyser under environmental threat.

This incredible collection of vintage pinball machines can be played at 25 cents a pop.

A much more welcome kind of snowbird vacationer, manatees camp out in these springs every winter.

Stepping away from the glitz of mobsters and casinos to learn about the other history of Vegas.

A museum and shop on Bourbon Street located in the French Quarter.

In all of the 29 years it was in operation, no prisoners ever escaped successfully... or so they claim.

Flashy signs from Las Vegas’s past find their final resting place at this unusual graveyard.

Speak to a companion on the other side of the room loud and clear through this architectural anomaly.

A free, canine-friendly alternative watering hole near the more famous Barton Springs.

Home to an endangered salamander, a full moon celebration, and a large spring-fed outdoor swimming pool.

Locals dubbed it the "Owl Building" because of its bird-like appearance.

Home to the largest urban bat colony in North America, estimated at 1.5 million bats.

This Arkansas town is known for its gangster history, its healing waters, and now its brews.

Mobsters came for a soak in the hot springs, and stayed for the illegal gambling and bootlegging.

The 10th-tallest pyramid in the world, this former sports arena is now home to a massive Bass Pro Shops store.

Alongside this Memphis trail are several sculptures that show trail-goers how to relax.

Elvis's own personal tropical hideaway.

Home to the world's largest refracting telescope and the birthplace of modern astrophysics.

An unusual statue in Wisconsin of the first daily comic strip character.

A bizarre roadside attraction and the first instance of miniature golf in the world.

The enormous 250-room Vanderbilt mansion conceals hidden doors and secret passageways.