This cluster of little wooden huts once ground local farmers’ wheat into flour during the days of the Austro-Hungarian Empire.

A uniquely lettered street sign marks the corner where the iconic word game was invented.

This small, hidden cove is home to abandoned boats.

America's oldest Eastern European synagogue provided the immigrants of crowded Lower East Side tenements a space of sanctuary.

A former insane asylum despised by Nelly Bly and Charles Dickens is now fashionable apartments.

Spinning silently in the lobby of an Art Deco masterwork is a massive vintage model of the Earth.

A bit of retro transportation flair preserved in the world's largest department store.

This mosaic dedicated to John Lennon was tended for years by a Beatles super-fan.

Once the tallest building in the world and the site of "the highest dinner ever held in New York" this building now holds the most expensive penthouse in the city.

This empty Victorian manse on Staten Island is said to be haunted but is actually a real life crime scene.

The name of this famed hospital was once a byword for the horrors of medical and psychiatric care.

Wall Street has a new heroine, a bronze statue of a small but fierce girl.

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

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

Elevated freight railway turned wildly successful urban park.

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

Try not to get slimed in Tribeca.

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

A treasure trove of artifacts, books, and artwork from the "golden age" of exploration.

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.

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

This "City of Books" holds a museum, library, and the complete personal book collections of five of Mexico's greatest thinkers.

These biodiverse university gardens form a green oasis amid the urban chaos of Mexico City.