Once the smallest park in the national system.

The beloved statue at the National Academy of Sciences is oh so inviting to sit on.

The land is home to swimming ponies and a legendary 18th-century treasure.

The graveyard holding the remains of George Washington's slaves was forgotten for nearly 200 years.

The tomb was guarded by soldiers from both sides of the war, and some left their initials carved in the brick.

The 5.5-mile ring of steel posts around the Capitol Building is one of the largest (and most uniform) of its kind in the world.

Corn-inthian columns with a uniquely American take on neoclassical architecture.

Members of Congress have traveled between the buildings on Capitol Hill for a century hidden from tourists, press, and storm clouds.

"Congress may voluntarily remain in session throughout the summer, in order that our Congressmen may be protected from the intolerable discomforts and dangers of the ordinary outdoor weather!”

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

Perhaps the most scandalous statue of America's first president.

This taxidermy horse was a Civil War hero.

A tiny monument to the unsuccessful attempt by Thomas Jefferson to place the prime meridian in Washington.

Look closely and you’ll notice that the color changes a third of the way up the tower.

Legend has it that President Grant’s frequent drinking in the lobby gave rise to the term “lobbyist.”

Abandoned silver mine strewn with wrecked and twisted structures.

This 19th-century ranch is being transformed into a residential library with thousands of books about the natural world.

Small teepee-like houses built for TB patients have become sheds, studios, and bus stops around Colorado Springs.

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

One woman's UFO-themed campground, complete with self-built energy vortexes, UFO-themed weddings, and magic bushes.

A short but powerful waterfall resides amid Colorado’s Great Sand Dunes.

When ecosystems collide in the arid Southwest.

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

This small piece of railroad history sits behind the parking lot of a chain grocery store.