Danish tourist destination well known for open stalls where vendors sell marijuana on the street.

It is said that each of the white stones in the red facade of this medieval house represents the head of a murdered Swedish noble.

Sweden's "good old days" painstakingly re-created in a model village.

A hidden bathhouse in one of Stockholm's oldest and busiest neighborhoods is open to anyone who can find it.

It houses the remains of a 17th-century version of the Titanic.

The world's largest model of our planetary system.

An ancient and majestic fortress that played an integral role in Portugal's road to independence.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

The vast, legendary catacombs hold secrets much stranger than stacked bones.

This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

Giant, friendly pelicans in Central London, the most unlikely of places.

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

A collection dedicated to the treatment of disease, held in London's oldest hospital.

Eighty million natural history specimens call this gargantuan museum home.

Hear the quietest sound from across the dome.

The only university zoological museum in London houses extinct animals, bizarre natural history specimens, and a Micrarium of microscopic creatures.

Banksy gives themself artistic license with this piece of London street art.

A hands-off space for graffiti artists to hone and display their skills.

This shop and gallery is a modern-day cabinet of curiosities, unassumingly positioned along an urban thoroughfare.

Metro station with a claim to rock n' roll fame.

Cold war icon and onetime "hole" in the iron curtain.

One of downtown Berlin's last reminders of its Communist past.

This water-tower-turned-high-end-apartment building was once the site of an early Nazi concentration camp.

The walls of Germany's Parliament still show the scars of the Red Army takeover in World War II.