The remnants of two World's Fairs are here, complete with a 12-story globe, a mini-Manhattan, and a UFO-shaped pavilion.

On the Hudson resides one of the largest clocks in the world.

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

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

This unmarked and unloved Manhattan subway grate created one of the most iconic images in American cinema.

A famous songsmith's custom piano, dubbed "High Society," is hidden just out of sight in one of New York's finest hotels.

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

Elevated freight railway turned wildly successful urban park.

This sculpture by artist Fritz Keonig survived the 9/11 attacks and now stands as a monument to the victims.

Built hundreds of years ago this downtown iron barrier once protected a much despised king.

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

Unrepaired walls from a 1920 anarchist bomb attack.

An odd, ancient window that may have once been part of a brutal prison is embedded in the side of New York's Police Plaza.

World's largest working waterwheel has been around for over 150 years.

Seat of the Duke and Duchess of Devonshire for centuries.

Eyam took steps to quarantine themselves and keep the plague from spreading.

Semi-precious Blue John stones have been mined in this cavern system for centuries.

Manchester's abandoned train depot lingers in a post-industrial purgatory.

A Victorian Gothic masterpiece housing a world-class collection of rare books and manuscripts.

The gloomy ruins that inspired Bram Stoker to bring Dracula to life.

Once a farm where patients tilled the soil, this asylum lost its workforce when overmedicating became common practice.

This sculpture is an instrument played by the swell of the seas.

A metal tree emits eerie, melodic notes on top of Lancashire's Crown Point.

Once thought to be the mysterious work of a witchy prophetess, a well with unusual properties turns objects into "stone".