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

A Pythagorean funhouse that tries, successfully, to prove that math is the coolest thing ever.

Order scoops of pandan, lychee, and black sesame at this family-run institution.

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

A New York garbage depot holds a secret collection of weird and wonderful refuse.

The feral felines of Roosevelt Island have a small army of allies and an abandoned hospital all to themselves.

This lower Manhattan bar is set up in an old bank vault that rests beneath a skyscraper that hides even more historic splendor.

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

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

Try not to get slimed in Tribeca.

Manhattan’s Battery Park has a whimsical carousel full of spinning, glowing fish.

The oldest family-run luncheonette in New York, last renovated in 1948, still serves food and drinks the old-fashioned way.

Dodge prohibitionists and slide through the telephone booth in Crif Dogs.

This beautiful building in the heart of Manhattan's Financial District was empty for decades.

Amid the bustle and noise of the Financial District hides a secluded garden oasis above the city streets.

A crumbling hospital from the 1850s on Roosevelt Island.

La Monte Young and Marian Zazeela's "Dream House" will immerse you in an ever changing world of sound and light.

A terrific purveyor of natural history objects and curios.

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

The iconic D.C. restaurant where the Cuban Missile Crisis was negotiated, now a Walgreens.

The former home of Lillian Evans Tibbs and her grandson, Thurlow Evans Tibbs Jr., whose prodigious contributions to music and art spanned more than 90 years.

Now a living classroom, this house was once the home of Reverend James Clinton Dent, a formerly enslaved man and a pastor.

An echo chamber with a waterfall wrapped around its base at the Embassy of Canada in Washington, D.C.

The word "Watergate" will forever be associated with the infamous scandal in 1972, but this fountain is famous in its own right.