The hidden offices underneath Memorial Bridge have been locked up since 1976.

A hoard of sky catalogs, astrophysical journals, even the works of Galileo and Copernicus.

This stunning blue and gold room changed cities twice before becoming part of the Smithsonian.

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

Franciscan monks created a facsimile of the Holy Land for North Americans who couldn’t afford the trip overseas.

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

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

The United States Capitol's former columns still stand.

Approximately 250,000 people left homeless by the great earthquake and fires found shelter in Golden Gate Park.

A man-made island in scenic San Francisco Bay.

Not merely a museum – but a whirring powerhouse that offers a subterranean peek into the heart and soul of cable car operations.

San Francisco's urban bison herd has persisted in the face of extinction, development, and disease.

A 300-ship graveyard, with a few still visible at low tide.

The last remaining relic of San Francisco's glittering 1915 Panama Pacific Exposition.

An essential stop before plundering, BYO Cutlass.

The humble fort that saved Washington.

2,000 barrels of aging beer hidden in a warehouse at the Brooklyn Navy Yard.

Pulled from the rubble of one of the worst modern tragedies, a steel crossbeam became a symbol of hope for New Yorkers.

An abandoned subway tunnel that could have reinvigorated Staten Island still lies somewhere beneath this Brooklyn park.

A museum collection honoring the long history of the FDNY is held in a disused Manhattan fire house.

Underground vaults of a former brewery beneath Brooklyn's Crown Heights are now used to ripen cheese.

Hear the tales of New York's most notorious criminals.

Once America's longest-manned military fort, now an abandoned hulk.

Lie in a hammock where George Washington stood.