Hidden in plain sight on the Hudson River is an abandoned train station where nature has taken over.

Constructed in the 1920s, this former pencil factory is now an office building.

The oldest surviving bridge in New York City, which reopened to pedestrians in 2015.

A Manhattan office building is home to the world's largest chess board.

This Parisian café sticks almost exclusively to an ethos of reuse.

An artist's cute bronze subway sculptures belie his violent artistic past.

At Chicago's revered Field Museum, visitors are invited to learn about and literally explore DNA.

Where Cusack's record store from the film "High Fidelity" was located.

Beloved bar home to musicians of all eras and reputations.

Parking lot where a Chicago mayor was inaugurated under very sketchy circumstances.

This shop for all your super spy needs hides an educational secret.

Where old school Polish Chicago and young hipster Chicago live side by side.

A gothic church spire sits atop this skyscraper, the tallest church in the world.

Four glass boxes hover over 1,000 feet in the air to give visitors an unparalleled view of Chicago.

A Museum of Holography frozen in 1974.

A little lighthouse in New York City, surrounded by mysterious stories of insanity-driven construction.

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

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

This abandoned subway station beneath the Waldorf-Astoria hotel is allegedly used to secretly transport presidents.

A crumbling hospital from the 1850s on Roosevelt Island.

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

Site of the first pathological and bacteriological research facility in the United States.

One of only two commuter aerial tramways in the United States.

Storage warehouse of the rich and famous.