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

There's a 12-foot-tall replica of the Washington Monument hidden under a manhole nearby.

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

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

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

There’s a hidden military meme engraved on the World War II Memorial.

This mysterious structure by the Washington Monument is a flood barrier designed to protect the White House against rising waters.

The monument's pointy aluminum tip has been melted down by repeated lightning strikes.

A cavernous three-story, 43,800-square-foot basement that was forgotten about for 60 years.

This fort down the Potomac from Washington, D.C. was once the only defensive fort protecting the capital.

This rare triple-jurisdiction drawbridge passes through Virginia, Maryland, and Washington, D.C.

America's first federal monument.

Recorded as the first person buried in Arlington Cemetery.

The controversial urban planner who designed Washington, D.C., was buried in Maryland, and can presently be found in Virginia.

Soldiers were buried next to Lee's house in the center of Arlington Cemetery to dissuade the general from reclaiming his property after the war.

The only surviving piece of a submarine said to be the most decorated vessel in U.S. history.

This impressively large collection includes crackers shaped like Jimmy Carter, Mickey Mouse, and more.

Train debris from the deadliest avalanche in United States history can still be found in the ravine where so many perished.

"The Reptile Man's" very own roadside zoo features an albino alligator.

Bird dung painted this huge boulder which in turn inspired the name of a city.

This statue and its surrounding plaques tells the story of Ko-kwal-alwoot and the kinship between the Samish people and the sea.

Sleep beneath the big screen at this old-school movie theater.

Now housed in a museum, this giant pink elephant stood in downtown Seattle for more than 60 years.

This former coal gasification plant found a curious second life as a popular public park.