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

There’s a secret bunker inside the Brooklyn Bridge, but the city won’t say where.

A WWI fighter plane and turn-of-the-century penny candy shop are among the unexpected features of this Financial District building.

A beautiful and abandoned New York subway station from 1904, complete with chandelier.

A clock set into the concrete outside a Manhattan jeweler has been telling time underfoot for over a century.

There just so happens to be a court even higher than the U.S Supreme Court: a basketball court in the building itself.

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

Where the U.S. government kept its actual treasure, before Fort Knox.

The bank that helped fund the Mexican-American War and the purchase of Alaska met its downfall after helping Augusto Pinochet launder money.

"Congress may voluntarily remain in session throughout the summer, in order that our Congressmen may be protected from the intolerable discomforts and dangers of the ordinary outdoor weather!”

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

A hidden gem on the lawn of the U.S. Capitol Building designed by landscape architect Frederick Law Olmsted.

An unassuming, powerful monument north of the U.S. Capitol bears witness to the resilience of Japanese Americans during a time of grave injustice.

The actual model from the original "Star Trek" series is now on display at the National Air and Space Museum.

This imposing Masonic temple a mile from the White House was the first public library in Washington, D.C.

The monument's pointy aluminum tip has been melted down by repeated lightning strikes.

There's a 12-foot-tall replica of the Washington Monument hidden under a manhole nearby.

This grand gothic brewery has been pumping out suds for over a hundred years.

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