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.

Bizarre lunar-like landscape with thousands of large stone "hoodoos."

Designed by Buckminster Fuller, this relic of the 67 Expo survived fire and ice.

A Montreal deli that was so beloved that it was allowed to circumvent their laws of language.

The biggest museum dedicated to insects in North America, one of the largest in the world.

What was once a trend-setting, phrase-coining icon of architectural splendor is now a rotting, forgotten hulk.

A once crucial portion of the Long Island railroad still lays abandoned, waiting to be turned into an urban park.

The haunting, dilapidated remains of a former poorhouse on Staten Island's Greenbelt.

During the Industrial Revolution this “Temple of Invention” was full of intricate miniature machines and gadgets.

After over 100 years out of service this landmark windmill once again turns as a symbol of Jerusalem's self-sufficiency.

A "miracle" that seems to produce more holy fistfights than holy revelations.

An ancient tunnel in Jerusalem built to redirect water in the event of a siege is one of history’s great architectural innovations.

Before Metro, Washington had a robust streetcar network—and you see the remains of this infrastructure if you know where to look.

The United States Capitol's former columns still stand.