A mysterious castle built as a monument to lost love.

One of the most scenic stretches of road in America winds between some of the country's oldest trees.

Strange red rock formations that have been attributed to a higher power for hundreds of years.

If drivers cross the rumble strip on this stretch of Route 66 at just the right speed it plays "America the Beautiful."

The angel of death appears to weep black tears at this grave marker.

Aqueducts have dramatically changed this old lake, now home to tufa towers and its very own species of tiny brine shrimp.

Rustic natural hot springs in the deciduous rain forest.

Frank Lloyd Wright's most iconic home dangles over a Pennsylvania waterfall.

This naturally-sourced hot spring is now home to a clothing-optional resort.

Franciscan monks created a facsimile of the Holy Land for North Americans who couldn’t afford the trip overseas.

Breathtakingly blue walls shimmer inside the "Glacier Behind the Town."

Oregon's unexpected high desert, displaying layers of time in a colorful show.

Ninety feet off the valley floor is an ancient dwelling put under protection of the U.S. government by Teddy Roosevelt.

Quite simply the largest tree in the world (by volume).

A hidden network of subterranean passageways lies tangled beneath Indianapolis' bustling City Market.

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

Where manatees are the snowbird vacationers in these balmy Florida springs.

Carved by a waterfall in a hard-to-reach rock formation, this heart-shaped rock has inspired romantics for decades.

These delicate buggers are some of the rarest fossils that have bubbled up from the Tar Pits.

This knobby, drooping New Orleans oak is a favorite place both for climbing and for meeting giraffes.

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

Hidden in Central Park's Ramble is a troublesome cave buried just beneath the surface.

In the middle of an extremely unforgiving and desolate high desert is the most secret military facility in the world.

The second-largest cave chamber in the world was discovered in 1898 by a 16-year-old and a friend known as "Pothead."