This was one of the first (and last) university-built and operated nuclear reactors.

The oldest living organism in New York City. Maybe.

Hidden in plain sight on the Hudson River is an abandoned train station where nature has taken over.

A fountain standing as a testament to a doomed alliance.

A grand New York post office that is home to mailman Santas, scraps of postal history, and a pneumatic mail system.

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

Reclaimed by nature, the ruins of Doodletown, New York are remnants of a town consumed by a state park.

Mysterious stone tower featured in many alternative histories of the New World.

A discreet little stairway on St. Nicholas Avenue leads to a quaint and unexpected cobblestone street of 19th century wooden rowhouses.

A stunning, two-tiered waterfall made famous by poets, artists and the legend of a ghost dog.

Vacant Beaux-Arts buildings that serve as reminders of a beach town’s glory days.

The only visible piece of San Francisco's most famous shipwreck.

The only intersection in America where the buildings on all four corners were built pre-Revolutionary War.

A starship has landed in Texas, a welcome break for weary travelers from a drab stretch of I-35.

A strip of modern stores in historic buildings.

Commemorating the spot where the famous scientist fed his pigeons.

A very classy 1920s-era bar right in Grand Central Station.

Lie in a hammock where George Washington stood.

There must be a pun in this haystack somewhere...

Set sail on a small scale.

Walk into the 19th century without leaving Brooklyn.

Hiroshima survivor on Riverside Drive.

Hundreds of antique bank vault locks on display in New York City.

Waterway populated with abandoned projects, including a submarine.