World's largest cave was only discovered in 1991, and now offers tours to the public.

This abandoned caretaker's apartment is one of 13 left in the New York Public Library system.

A winding, cliffside stretch of road overlooking the Delaware River.

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

One of only two remaining Victorian-era greenhouses in New York.

The home of one of America's most wealthy industrialists is now a historic site that remembers a more decadent time in the country's history.

Not even a series of devastating fires could keep this odd castle in upstate New York from bouncing back.

This outdoor gallery of graffiti-covered walls pays homage to the past, present, and possible future of street art.

Comprehensive gaming collection of over 30,000 electronic games and consoles.

A small peaceful park and waterfall tucked amid the urban grind of Midtown Manhattan.

This old cement mine has been used as everything from a mushroom farm to a recording studio.

This otherwise innocuous bodega was once the headquarters of the most feared assassin's guild in American history.

This historic address is home to the beloved ball and is an almost totally empty building among the most expensive real estate in the world.

An annual extravaganza of Broadway theater memorabilia.

The absurd creation is a compulsory destination for selfies in Buffalo.

Hear the tales of New York's most notorious criminals.

America's greatest forgotten garden and the former stomping grounds of Son of Sam.

The site of a tragic massacre that spawned a multimedia franchise.

A hyper-luxurious, 12,000- square foot home might be buried beneath Queens, still waiting to protect you from nuclear missiles.

You can still ride this 100-year-old work of art in Brooklyn's largest public park.

This wall on a street corner in Lower Manhattan has been a blank canvas for a rotation of renowned artists since the 1980s.

Avoid gangster interaction while window-shopping.

The crown jewel of the Queens Museum is a nearly 10,000-square-foot architectural model of the city originally built for the 1964 World's Fair.

A ruined mansion hidden in the woods of the Hudson Valley, home of a tragically doomed romance.