Hidden in Central Park's Ramble is a troublesome cave buried just beneath the surface.

Built as a gift to the hottest tastemaker of the time, these hidden quarters remain an Art Deco showpiece.

A tiny museum housed in a New York freight elevator specializes in the "overlooked, dismissed, or ignored."

Try not to get slimed in Tribeca.

Built hundreds of years ago this downtown iron barrier once protected a much despised king.

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

Revolutionary War casualties fill the only 17th century structure remaining in Manhattan.

The last remnants of what was once one of the world's grandest hotels can now be found in a Manhattan subway station.

A recently abandoned psych ward at the end of Sanatorium Road.

The famous bell was secreted away and hidden in a church in Allentown during the British occupation of Philadelphia.

This semi-spooky remnant of an abandoned hotel provides fantastic views.

Mysterious rocks that ring musically when struck.

A surprising museum of 20th-century technology.

A drab two-story office space in Delaware is a hidden tax haven for Hillary Clinton, Donald Trump, and over half the Fortune 500 companies.

An extraordinary collection of vampire-themed antiques lurks on the second floor of a store.

These lush botanical gardens employ the most purrfect pest control force.

This palatial botanical garden is home to one of the largest pipe organs ever installed in a private residence, and a piece of Wood's cycad.

The headquarters of the Fraternitas Rosae Crucis, complete with Rosicrucian pyramids, all in the Pennsylvania woods.

A glittering Thai Buddhist temple in suburban Pennsylvania.

A modern ghost town whose inhabitants were driven away by the growth of nuclear power.

The first American department store, and home to the largest operating musical instrument in the world.

The world's third-largest crystal sphere has sat in the Penn Museum since 1927 with the exception of one outlandish theft.

The humble field where the first Major League Baseball game was played.

Century-old shop, specializing in Occult products.