Eighty million natural history specimens call this gargantuan museum home.

This site contains overlapping ancient graveyards that existed about 1,000 years apart.

The location of this historic castle was inspired by a donkey.

An ancient and majestic fortress that played an integral role in Portugal's road to independence.

This unreal Portuguese palace looks as though it's made from a pile of different castles.

Elaborately carved to showcase the glorious wealth that the age of exploration brought to the Portuguese empire.

A king's pet, a pope's gift, an artist's inspiration, and a tragic shipwreck.

The hippo that stands on this university campus was once a drunken flea market purchase.

The National Park Service’s best-kept secret with views that rival any in D.C.

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.

An overlooked memorial honoring the local Washington residents who died in World War I.

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

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

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

Those with a sharp eye can find the hidden image of a German Shepherd on the memorial's Mural Wall.

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

The national park was once a plantation estate.

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

A museum cafe showcases Native American dishes and indigenous ingredients from across the Western Hemisphere.

Hidden within an idyllic suburban garden is a memorial dedicated to the victims of a terrifying spree of killings committed on U.S. soil.

The 72-foot giant escaped confinement in a large patch of mulch only to be reburied in the sandy shores of the Potomac River.

The childhood home of the Sultan of Swat is just a line drive away from Oriole Park at Camden Yards.

Rediscovered after a century, the father of the American Navy was reinterred in something dredged up from Davy Jones' Locker.

Home of a French nobleman's short-lived attempt at raising cattle in the Badlands of North Dakota.