World War II-era bunkers are hidden under the beaches of this picturesque park, which is still scattered with wartime watchtowers.

The only remaining building in New York to see the inauguration of a president is being slowly overtaken by a grocery store.

The only presidential monument to display a late POTUS's actual casket.

The statue of John Harvard isn't actually John Harvard—or even, technically, the founder of the school.

An interesting decoration on this historic site, this weathervane comes with as many legends as it does questions.

Funded by John D. Rockefeller, this is one of the earliest, and most beautiful, shopping arcades in America.

This spectacular public market has got meat, fish, vegetables, baked goods, and enough kielbasa for a lifetime.

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.

One critic described it as "middle Mussolini, early Ramses, and late Neiman-Marcus." Another called it an architectural "natural disaster."

Once a black market electronics marketplace, now an otaku shopper's paradise.

A Beaux-Arts triumph rises from decades of decay to become the heart of a new innovation district.

These enduring murals depicting a distinctly Marxist tribute to capitalism could not even be defeated by McCarthyism.

An uber-secure, windowless tower of doom in the center of Manhattan is an NSA spyscraper.

Parking garage where Bob Woodward met Watergate source "Deep Throat."

The world's oldest continuously operating airport was founded by the Wright Brothers.

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

Every drop of D.C. tap water flows through this old waterworks.

D.C.'s first central library was born out of a chance encounter with the philanthropist whose name it bears.

These numerous Israeli caves were dug out over hundreds years for reasons ranging from hideouts to burial sites.

The bridge's highly-contested plaque (once again) honors Confederate President Jefferson Davis.

The only road through the heart of Glacier National Park.

Britain’s longest ancient monument, this great 8th century earthwork was built to mark the boundary between what would become England and Wales.

A walk-in working camera obscura produces 360-degree live images of the San Francisco coast.