Where a railroad loops under or over itself to rise or drop more than 70 feet in a short distance.

One of the last free public hot springs is decorated with hippie art.

An underground river pushes more than 200 million gallons out of this Missouri spring every day.

An impressive waterfall nestled in the cliffs of Idaho's Snake River Canyon.

“You better take care of me Lord, if you don't you're gonna have me on your hands.” ― Hunter S. Thompson, Fear and Loathing in Las Vegas.

Even in death, he's still your huckleberry.

The site of a defunct mill, that once supplied marble for the construction of the Lincoln Memorial.

Despite being one of the most photographed vistas in the Rockies these twin peaks are rightfully known as the "Deadly Bells."

A little-known hot spring haven right below the highway.

Crystal clear lake with a shoreline of travertine located in a Colorado canyon.

This dry lake bed contains the oldest known petroglyphs in North America.

The lynching and burial site of America's first train robbers.

At the turn of the century, a chair like rock sat at the top of the falls and hosted the winner of a local beauty contest.

This abandoned bridge over the River Irvine may be the oldest surviving railway viaduct in the world.

One of the first canal boat-lift inclines ever created.

These unique rock formations were created during the Ice Age.

This cascade of mineral-rich hot springs and waterfalls is an oasis in the Jordanian desert.

This "castle" is actually a limestone and quartz formation hidden along a trail.

This preserved wilderness hides the remains of a colonial grain mill used to feed George Washington's troops.

Trek through the jungle on a boat and a swinging bridge and you'll be rewarded with these refreshing, if pungent, mineral pools.

Often referred to as the largest spring in America.

A magical oasis in the middle of the Negev Desert.

Every half hour, the flow of this unusual spring cycles between a rush of water and barely a trickle.

This small turbine mill along Rocky Creek was built in 1928