Planes, trains, and automobiles have all been sunk as attractions at this Illinois diving spot.

Often referred to as the largest spring in America.

The largest riverfront opening cave in the Ozarks.

An average of 33 million gallons of water pour out of the collapsed cave at the heart of this spherical spring.

Around 50 million gallons of water flow from this spring every day.

Erosion and time have created a naturally-formed water park.

This crumbling UFO is one of only a few remaining "moveable ski chalets" of its kind.

This strategically-placed fountain creates the magnificent illusion of mustangs galloping across a river.

A Victorian mansion, painstakingly reproduced to appear just as the the Munster's family home did on TV.

Craggy concrete faces are hidden in the walls of this artificial cave along the San Antonio River.

A gorgeous garden oasis with winding paths, stone bridges, and a troubling history.

These boots are made for selfies.

Over 100 million years ago, beach-bound dinosaurs left permanent marks on San Antonio's landscape.

The summer home of the largest colony of bats in the world.

Moonbows over Kentucky.

Abandoned railroad tunnel is home to a colony of three million Mexican free-tail bats.

One of the highest points in Bexar county offers birdseye views of San Antonio and a four-story stone tower.

This underwater old Texas hill town only resurfaces during harsh drought.

Civil War dumping ground for the bodies of terrorized Union sympathizers.

An emerald-green grotto just a short trip from Austin.

This beautiful grotto is one of those places where you can't believe you're just outside Austin.

A popular swimming hole that hides one of America's most deadly diving spots.

Housed in a century-old building, this museum's dedicated not just to soft drinks, but to the free enterprise system.

Visitors can walk over the largest concentration of Columbian mammoths to have died from one event.