Hear the quietest sound from across the dome.

The perfectly preserved underground rooms where Churchill plotted the war against Germany.

Kings Cross Station pays tribute to its role in Britain's best-selling book series.

All unmarked mute swans on the Thames are owned by the Queen per a tradition that began in the 12th century.

A replica of the steam engine that hauled Queen Victoria's Royal Train is on display at Windsor.

This 11th century tower is said to be the oldest building in Oxford.

One of Europe's oldest libraries.

J.R.R Tolkien, C.S. Lewis, and other "Inklings" met at the Oxford pub to discuss the now legendary fantasy stories they were writing.

Eighty million natural history specimens call this gargantuan museum home.

The watery entrance for condemned prisoners heading to the Tower of London is still visible along the Thames.

Six ravens are kept captive (but well-fed) at the Tower of London to prevent the fall of the Crown.

The grave of America's 11th president is not in some grand monument but instead it's hidden away on the grounds of the Tennessee Capital.

The small cave that housed Tennessee's "first citizen."

The original Garfield station is the oldest station facility on the "L", with the station house dating from 1892.

These chunky stone towers out in Lake Michigan are the key to Chicago’s drinking water.

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

To find the "unicorns of the deep" you've got to go downstairs.

The world's largest floating loon bobs in the lake to kick off an annual festival.

One of the few remaining relics of the meatpacking hub that made Chicago the "hog butcher to the world."

The enormous 250-room Vanderbilt mansion conceals hidden doors and secret passageways.

The study has wall paneling from a 17th century ship.

This church houses the “incorrupt” body of its founding Bishop.

This simple gravestone remembers a pig who single-hoofedly raised $19,000,000 for the Navy.

This rare vessel mixed luxury with labor before being converted to a museum and sometimes haunted maze.