The highest point in Washington state is a volcano covered in glaciers.

The only road through the heart of Glacier National Park.

The only royal palace on U.S. soil has been a territorial capitol, a military headquarters, and a prison for a queen.

This black shoreline is made up of exploded lava particles.

This awkward aquarium sculpture is one of the strangest statues in Chicago.

The unluckiest U-boat in the entire German fleet is now on display in a Chicago museum.

This Yellowstone geyser may not shoot as high as the nearby Old Faithful, but it erupts for considerably longer.

One of nature's most well-scheduled phenomenons resides in Wyoming's Yellowstone National Park.

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

The first declared National Monument in the United States.

The most powerful laboratory radiation source in the world pulses with 1,000 times the electricity of a lightning bolt.

This museum started as a collection of Manhattan Projects and continues to add exhibits as they are declassified.

A unique geological area spiked with wind-carved rocks that resemble teepees.

The official atomic museum of the United States explores the explosive and productive history of a much maligned energy source.

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

A multi-storied adobe complex has been inhabited for more than a thousand years.

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

Explore the largest pure gypsum deposit in the world, and go dune sledding while you're at it.

This two-room shotgun shack in Tupelo is the birthplace of a King.

The world's tallest doric column is this Ohio monument to a naval victory in the War of 1812.

The spectacular collection of one of the world's best woodcarvers.

Ghost stories surrounded this “castle,” the only structure from a huge mansion that was never built.

Funded by John D. Rockefeller, this is one of the earliest, and most beautiful, shopping arcades in America.

Rare recess caves fill this unbelievably beautiful Ohio park.