More than 2,000 species of tropical plants call this nature preserve and sanctuary home.

A small metropolis of Pueblo cave dwellings have been carved right into the hillside of this national monument.

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

A spiritual vortex among the red rocks in Sedona.

These crudely shaped folk giants may be the the second most photographed statues in the U.S.

At this Minnesota state park you can easily wade across the source of the mighty Mississippi.

Members of Congress have traveled between the buildings on Capitol Hill for a century hidden from tourists, press, and storm clouds.

The land is home to swimming ponies and a legendary 18th-century treasure.

The largest university building in the West is a gothic masterpiece containing dozens of theme rooms based on different countries.

One of the steepest streets in the United States makes an intriguing challenge for cyclists.

This quarter-mile tunnel under the Bluff in Pittsburgh bends at a 45-degree angle.

The United States’s oldest funicular railway glides up and down a steep Pittsburgh street.

The last remnants of Fort Pitt also hold the distinction of being the oldest structure west of the Allegheny Mountains.

There aren't too many operational funiculars around, but Pittsburgh has two!

An Iowa town celebrates its heritage with the tallest working Dutch windmill in North America.

This double-arched masonry highway bridge is the only structure of its kind in Minnesota.

A roaring, awe-inspiring double cascade of icy water flows through woodland Oregon like something out of a Tolkien novel.

The magic's in the hole!

Walk through the actual strap iron cells and solitary chambers of Arizona Territory’s first prison.

Come for the pizza, stay for a performance on the world's largest theater pipe organ.

A Mexican Romeo-and-Juliet-esque legend has given this super-narrow alleyway a reputation for romance.

Mexico's astounding mummy museum with "the world's smallest mummy."

This huge green space packed with activities will make you forget you're in the middle of the Ecuadorian capital.

Massive volcano in the Andes is the farthest point from earth's center.