A layered tribute to the work of mosaicist Isaiah Zagar.

The world’s first penitentiary, meant to be humane, drove men insane.

The only Civil War battle in Washington D.C. took place near this highest natural point in the city.

A Civil War fort in the middle of Washington, D.C. has been swallowed by a forest.

Long-abandoned trolley tunnels just a mile away from the White House are turning into an art space.

Home to items never before seen by the public.

The site of the climactic scene from the classic horror film is now a historic landmark.

The Corinthian columns that towered over Abraham Lincoln’s inauguration stand proud.

Washington's top-secret Cold War-era doomsday communications tower is located in a small neighborhood park.

The building features one of the last remaining free-floating spiral grand staircases in the U.S.

City Council meetings still happen in this historic building, impeccably preserved on the inside.

An abandoned network of military bunkers and tunnels open for anyone willing to descend into the darkness.

From overly ambitious (and eventually abandoned) atomic dream to bustling office park.

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

100-year-old shipwreck you can walk up to at low tide.

Where Nor'easters go to die.

This gorgeous beach hides behind two headlands in Oregon's Ecola State Park.

The wooden airship was the largest flying boat ever built.

Two massive rock outcroppings on the Oregon coastline.

The eerie remnants of an ancient forest were hidden under the sand for centuries.

The first North American landing spot for James Cook on his third voyage of discovery in the Pacific.

One of the most scenic stretches of road in America winds between some of the country's oldest trees.

The lighthouse central to the 1980s horror classic "The Fog" is, in fact, located in one of the foggiest areas of the Pacific Coast.

A hidden subterranean installation offers a view of the sky.