A former electrical substation is now home to an eccentric junk art masterpiece.

This unique structure in suburban Austin is made up entirely of other people's castaways, and constantly changing.

A rotating cast of guys and dolls in front of a Washington, D.C. building.

Fittingly, America's museum of architecture is itself a magnificently designed old building.

A derelict bit of transportation infrastructure hidden in the woods.

A cavernous three-story, 43,800-square-foot basement that was forgotten about for 60 years.

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

With over 100 jam-packed rooms to explore plus elaborate tea services and events, the Mansion on O Street is a hidden treasure.

Read between the lines of the subway map to find the hidden abandoned Civil War fort.

A wondrous old library overlooking the nation's capital.

Home to the infamous "Typhoid Mary" and the worst loss of life in New York's history prior to September 11, 2001.

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

A historic neighborhood church is reborn as a psychedelic arts collective.

A masterpiece of LGBT art has been restored in what may now be the most valuable restroom in America.

From scholastic to sepulchral - now under reconstruction.

The sci-fi villain is a little-known inhabitant of the U.S. capital's largest cathedral.

Mural made of 100,000 pieces of hand blown glass, and until recently, the largest glass mural in the US.

Enormous piles of historically significant stones, dumped by Congress in a forest, and abandoned for 60 years.

A tiny piece of the Moon is embedded in this stained glass masterpiece.

The name of this famed hospital was once a byword for the horrors of medical and psychiatric care.

The world's oldest hologram gallery and the labyrinthine laser laboratory of a holography pioneer.

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

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

The abandoned husk of a mental institution that failed to save a Jazz Age icon still sits nearly unchanged.