This city square is home to Amsterdam's oldest church and a statue honoring Dutch sex workers.

This mosaic dedicated to John Lennon was tended for years by a Beatles super-fan.

Site of a classic 19th-century physics experiment to prove the earth is rotating.

Ancient snack bar of the Roman Empire re-opened.

A beautifully eclectic mix of architectural styles.

The celebrated eyesore created by starry-eyed sweethearts.

A series of waterfalls so massive they straddle the border of Argentina and Brazil.

One of the deepest indoor swimming pools in the world.

A serious museum dedicated to two German comedians.

Scattered throughout London are ancient remnants of the city's former bounding wall.

A 2000-year-old Roman amphitheater lies just below Guildhall Yard.

Famed architect Antoni Gaudi built this generous thank you gift to a friendly host who housed him during a job.

Cuba's historical trains remind natives of their country's sugary sweet past.

An old slave lookout in Cuba's historic sugar cane fields.

Site of James Cook's historic observations of the 1769 transit of Venus.

An underground city of salt.

This "dead marsh" sits among the largest sand dunes in the world, a forest frozen in time.

Stalin's march toward a more modern USSR flooded a monastery, leaving a unique and extravagant nautical marker, "The Flooded Belfry."

Come for the flowers, stay for the bats!

On the Spree bank, discover one of the last reminders of a symbolic wall that divided, and was torn down by the people.

St Bernard de Clairvaux Episcopal Church, better known as one of the oldest European buildings in the Western Hemisphere.

Curious crustaceans support an obelisk from ancient Egypt that now stands in modern-day Central Park.

Men in rubber-soled boots serve as your "brakes" on this toboggan ride Hemingway described as "exhilarating."

Model Trains and Much More in Hamburg.