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

The first declared National Monument in the United States.

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.

A beautiful geyser under environmental threat.

One of the dwarven trees dates back to 1625 and survived the Hiroshima bombing.

This old-fashioned carhop restaurant gave the world the waffle cone.

The air force base preserves its scars from the Japanese attack on Pearl Harbor.

The Corinthian columns that towered over Abraham Lincoln’s inauguration stand proud.

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

This 29-ton granite ball spins around at the slightest touch thanks to a scientific phenomenon.

The last holdout of a pre-Civil War rebel who took the matter of slavery into his own hands.

A priceless collection of the Nation's cryptologic history.

This stately building in Alexandria, Virginia was built by Freemasons to honor one of their most famous members.

A former major munitions plant that has been converted into a sprawling art space.

This lonely waterfront memorial to the men of the Titanic was erected by the "Women of America."

Washington's iconic carousel has a nice piece of Civil Rights history.

Home to items never before seen by the public.

A tiny piece of the Moon is embedded in this stained glass masterpiece.

The sci-fi villain is a little-known inhabitant of the U.S. capital's largest cathedral.

This pun was simply waiting to come to life, and one defense contractor made it so.

At 207 feet, one of the world's longest continuous escalators.

The semi-reclaimed ruins of this canal were once part of an ambitious plan to reroute the mighty potomac.

At Washington's Dulles Airport is a satellite museum (no pun intended) with three quarters of a million square feet of aircraft history.