Home to items never before seen by the public.

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.

This groundbreaking 16th-century map is known as "America's birth certificate."

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

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

On the Fourth of July this area will transform into a Pompeii-like storm of falling embers and ash.

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

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

Daredevil repair workers can worm their way out the access hatch, loop ropes over the apex and rappel down the monument.

A three-story tower of books about Abraham Lincoln is one of the more unusual monuments to the president.

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

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

The winding route passes through an enclosed alleyway, two tunnels, and leads to the White House basement.

Four bald cypress trees in Lafayette Square, across from the White House, mark the southern edge of a 100,000 year old cypress swamp.

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

The flock of plastic poultry is an ode to the classic comedy staple.

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

A museum dedicated to the history and exploration of both popular music and science fiction.

This museum devoted to the gothic author holds such interesting ephemera as his socks and walking stick.

An eccentric priest's tribute to George Washington, this chapel tells the story of the American Revolution.

Yo, Adrian!

World's first "penitentiary," meant to be humane, drove men insane.

A giant Troll lurks under one of Seattle's oldest bridges.

Statue of Lenin, from Cold War era Czechoslovakia, now in a neighborhood of Seattle.