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

Great place to have a drink and a bite to eat in an atmosphere laden with New York's Bohemian past.

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

A Pythagorean funhouse that tries, successfully, to prove that math is the coolest thing ever.

A daily replay of the experiment that proved the rotation of the Earth.

The sounds of the world's largest fully functioning pipe organ dazzle shoppers at a Philadelphia Macy's.

This elaborate towering structure was once famed for its revolutionary height.

The first American department store, and home to the largest operating musical instrument in the world.

This charming colonial alleyway is one of the oldest continuously used residential streets in the U.S.

Philadelphia boasts one of the best — and most often overlooked — traditional Japanese gardens in North America.

These medieval tunnels provided water to the city above through centuries of civil war and plague.

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

London's last remaining public soapbox site has seen speeches from Karl Marx, Vladmir Lenin, and George Orwell.

After nearly 60 years, there's still a bear at Paddington Station looking for help.

The Metropolitan Police refurbished the blue box (perhaps not coincidentally) the same year "Doctor Who" returned to TV screens.

This massive collection of British military artifacts includes the heartbreaking personal letters of the men in the trenches of WWI.

A cluttered and astounding collection of antiquities and curiosities.

Eighty million natural history specimens call this gargantuan museum home.

A charming 17th-century alley is lined with secondhand bookstores and antiquarian shops.

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

The largest greenhouse in the world is home to over one million types of plants.

How did this lovely seaside English village come by such an unusual name?

The first and only carousel with a lineup entirely of insects.

Every year model trains zip through a miniature New York City that's now 150 landmarks strong.