The honor of highest point in Michigan was almost given to the wrong peak before this mountain won out by 11 inches.

This observatory comes complete with three separate telescopes and a dedicated community of amateur and expert astronomers.

The Beaux-Arts aquarium boasts a vast collection of saltwater and freshwater fish on an island in the Detroit River.

Trails through lava-carved tube-caves display sparkling bacteria and a rich history.

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

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

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

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

A museum dedicated to the alleged Roswell Incident.

An acoustic anomaly with a mysterious cause.

The longest continuous lava tube in the continental U.S. offers 2.5 miles of dark explorations for the adventurous.

A modernist landscape of water and sci-fi concrete.

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

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

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

Seemingly grown on some other world, these New Mexico rock formations look like a disused science fiction set.

Towering basalt columns, a creation of fire and ice.

A beautiful geyser under environmental threat.

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.

This massive stained-glass masterpiece is thought to be the largest Tiffany dome in existence.

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

These remote Florida islands have a history of sea turtles and sunken treasures, and one of the world's largest coastal brick fortresses.

Most-visited and most-photographed slot canyon in the American Southwest.