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

This ruined fort hidden at the top of Central Park can't seem to keep from losing its historical plaques.

An unassuming secret door once led to a legendary watering hole.

Ride the subways of yesteryear.

This cemetery has graves dating back to the 17th century, including the city's oldest carved tombstone and an ominous cryptogram.

One of only two commuter aerial tramways in the United States.

This abandoned subway station beneath the Waldorf-Astoria hotel is allegedly used to secretly transport presidents.

Try not to get slimed in Tribeca.

A crumbling hospital from the 1850s on Roosevelt Island.

This relatively recently abandoned brewery is a tragic reminder of the continuing effects of Hurricane Katrina.

The state's oldest continuously operating museum houses more than 5,000 Civil War artifacts.

If New Orleans is the birthplace of the "cocktail," why does their own museum of cocktail memorabilia beg to differ?

A theme park that suffered massive flooding during Katrina was abandoned, and now proves irresistible to trespassing explorers.

World War II-era Nazi compound nestled in the Santa Monica hills.

This vintage car parts store is also a museum devoted to a squat little gem of automotive history.

A few iconic structures are all that remain of America’s first outdoor shopping mall.

This quirky UFO-shaped curiosity is often mistaken for the airport’s control tower.

Inside this clubhouse is a cinephile's paradise.

Secret US military film studio in the Hollywood Hills.

The illuminating collection of L.A. street lights is run by the city and only opens one day per month.

One of the world's largest collections of rare and magnificent bird specimens.

The famous animator's private station house and man-cave was the birthplace of imagineering.

Hidden above a drug store on a nondescript corner of Lincoln Heights is a private clubhouse for intrepid explorers.

A common entry point to the Griffith Observatory trail holds its own wonders.