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

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.

A bas relief commemorates the "Nuns of the Battlefield" who cared for soldiers on both sides of the conflict.

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

Largest Roman Catholic church in North America.

The walls of the iconic dome are hollow and have a secret stairway.

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

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

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

Home to items never before seen by the public.

The United States Capitol's former columns still stand.

Sharing the often-overlooked story of America's Black soldiers.

A tribute to the Nirvana frontman hides beneath the bridge that was the singer's beloved hangout spot.

The remains of this rugged homestead ranch offer a brief glimpse into a bygone era.

Religious statues built because of one man's bargain with God fill this peaceful sculpture garden.

In Tucson a giant metal snake helps pedestrians cross a busy highway.

The oldest apple tree in the Pacific Northwest.

Nestled between a college and a golf course, the garden is home to more than 2,500 rhododendrons.

Instead of fruit, the branches of this tree are brimming with hopes and dreams.

Delightful disarray of found objects and clutter.

The magic's in the hole!

A community gathering place that once housed half-ton tanks and the World's Fair.

This working class sculpture pounds his hammer all the livelong day.