Hidden in plain sight on a pair of Manhattan subway tunnels are a pair of public instruments that sing to each other.

Tucked in a nondescript downtown Brooklyn mall is a bar containing a remarkable turn of the century anatomical wax collection last seen in 1920s Berlin.

Home to the infamous "Typhoid Mary" and the worst loss of life in New York's history prior to September 11, 2001.

Holding the current title of "biggest chair in the world," it stands with little fanfare in Lucena, Spain.

Despite its grandiose name, this enigmatic first-century void under the town is no cave, and it's possibly not a palace either.

A micro-communist utopia in Spain with no police, no mortgages and full employment.

A large grotto built in the 16th century amidst Florence's famous Boboli gardens.

The middle finger of modernity.

Madrid's romantically ornate crystal palace has been offering shelter to plants and art for over a century.

Abandoned for decades, trains still pass through the now-restored remains of one of Madrid's first metro stations.