This historic Amsterdam bar used to accept sailor's monkeys as payment.

A hidden church in a hidden courtyard tells the story of the Miracle of Amsterdam.

In the days before house numbers, these colorful signs held clues about various buildings' purposes.

A Dutch passageway's artistic, aquatic-themed makeover pays tribute to the capital city's famed waterways.

The spectacular history of spectacles on display.

Three connected pink triangles memorialize persecuted gays and lesbians throughout history.

This iconic Parisian bookstore doubles as the "Tumbleweed Hotel" for traveling writers.

This ornate Victorian marketplace was the setting for Diagon Alley and the Leaky Cauldron in the Harry Potter films.

Once a train station along the Great Eastern Railway this vibrant coffee shop and bar is where members of London’s creative class mingle.

Thanks to modern navigational tools we now know that the true prime meridian runs through a park next door.

Claiming to be the oldest hat store in the world, this historic haberdashery had a hand (and a head) in the creation of the Bowler.

The final resting place to 300 Victorian-era pets hides inside the city park.

Catacombs turned marketplace.

London's creepiest cemetery was once the site of dueling magicians and mobs of stake-carrying vampire hunters.

Giant marble phalluses on the sacred island of antiquity.

This eccentrically decorated palace is replete with grottoes, fountains, tunnels, and caves.

This unreal Portuguese palace looks as though it's made from a pile of different castles.

Elaborately carved to showcase the glorious wealth that the age of exploration brought to the Portuguese empire.

A king's pet, a pope's gift, an artist's inspiration, and a tragic shipwreck.

Step back in time and witness the fall of Constantinople.

The largest 19th century panorama in the world still in-situ.

Most prolific publishing house in the 1600s open to the public.

A little sculpture with a large wardrobe.

Climb inside an iron crystal magnified 165 billion times its normal size.