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

One of the largest free-standing structures ever built, this dirigible hangar is now simply a giant skeleton.

This African beach is home to thousands of rare mainland penguins that are known for their annoying voice.

Rippling sand dunes frozen in the Arizona rock.

Stroll through a wonderland of stupendous moss-covered trees.

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

The central mosque of this Mali town is entirely built from mud.

A Japanese corporation has turned this small island town into living modern art gallery.

Dedicated to improving the plight of the rare scaly anteater.

An organ located deep within a cave, whose "pipes" are the geological features of the cave itself.

The largest island on the great salt lake is home to curious creatures and strange stories.

Giant, natural amphitheaters made of delicate geological formations called "hoodoos."

Step into the cool deep past and unknown future of who begat who.

A Mars simulation in the southern Utah desert.

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

Visit this playground of waterfalls, caves and sinkholes.

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

Hollowed out cedar log tubs set in an ancient towering forest.

A room in New York City that contains 250 cubic yards of dirt worth a million dollars.

One kilometer of thick brass rod laid out before your eyes.

A beautiful geyser under environmental threat.

Canyon walls shrouded in ferns.

In the remote high desert of New Mexico, a strange array of poles beckon fury from above.

An urban laboratory.