Eccentric concrete mansion and museum designed and built by hand from the inside out.

This charming colonial alleyway is one of the oldest continuously used residential streets in the U.S.

A stone arch leads to a cavernous 1930s spring house tucked away in the Pennsylvania woods.

Sail through this subterranean show cave that is home to a legend that would go on to name nearly everything around it.

Frank Lloyd Wright's most iconic home dangles over a Pennsylvania waterfall.

Tour the dark and beloved poet's former cobwebbed basement, which may have inspired "The Black Cat."

A toxic ghost town sitting atop a massive coal fire.

A three-story copper skybridge connects two Manhattan buildings with Art Deco luxury.

The "Seinfeld" diner.

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

This whimsical group of statues is a favorite of children who love to climb all over Lewis Carroll's beloved characters.

Ride the subways of yesteryear.

Whisper secrets in a busy station only to be heard on the other side of this acoustic arch.

A hands-on traveling collection of the innovative devices of yesteryear.

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

A semi-scholarly approach to sex.

A miniature rainforest is growing inside of a Midtown Manhattan office building.

Try not to get slimed in Tribeca.

The world’s oldest and biggest bookstore stocking only mystery, crime fiction, espionage, and thrillers.

One of the largest publicly funded mural in the country is one city's love letter to itself.

The art deco colossus played a role in war and medicine aside from hosting the iconic Louisiana Hayride.