See massive fossils that are over 200 million years old in northeastern Arizona.

The magic's in the hole!

A museum dedicated to the alleged Roswell Incident.

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

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

San Francisco's newly reopened hands-on science museum.

This whimsical group of statues is a favorite of children who love to climb all over Lewis Carroll's beloved characters.

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

The largest hot spring in the United States is, as the name suggests, a stunning show of natural color.

The world's longest known cave system.

Towering basalt columns, a creation of fire and ice.

Take a drunken tour inside the world's largest known geode.

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

Under a glass sidewalk lie the remains of some of Manhattan's oldest buildings.

A beautiful geyser under environmental threat.

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

The first declared National Monument in the United States.

The hike through a narrow river flanked by the 2,000-foot-tall walls of Zion Canyon is one of the best in the world.

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

Here, at the "world's longest art gallery," you'll find forty miles of ancient petroglyphs and pictographs.

Enormous lake at the bottom of a unique cave system.

The ancient dwellings of the Puebloans, located in the cliffs of majestic mesas.

Under the right circumstances, this waterfall in Yosemite briefly turns a luminescent fiery orange.