The de facto symbol of Copenhagen is this bronze fairytale which cannot seem to keep its head for very long.

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

Pigduck of Turku.

Historic slum of Tartu.

First point in the Struve Geodetic Arc, a 19th century undertaking to measure the Earth's size and shape.

Man-made mineral caves house massive bat colony.

The second largest in the world, this massive underground void has its own subway.

An ancient capital city that dates back 3,000 years and harbors many surprises.

Come for the flowers, stay for the bats!

This historic observatory contains the world's oldest refracting lens telescope.

The world's brightest bioluminescent bay.

The world's second largest single-dish radio telescope, once used to contact E.T.

A tree-like building perches on its trunk in the Steglitz neighborhood of Berlin.

A slice of central Asia in the middle of Berlin.

A preserved college lock-up that recalls a clubhouse approach to discipline.

Rock-hewn monastery complex with hundreds of cave structures tucked away into the mountainside.

Underground monastery and fortress.

A museum glorifying the life of Stalin, located in the city of his birth.

Ancient rock-hewn town that witnessed key events of Georgian history.

The charmingly disheveled clock tower of Tbilisi's puppet theater.

Ottoman-era houses lovingly preserved.

A Turkish monastery tucked into a cliff wall.

A gleaming white and undulating tower marks the border between Georgia and Turkey.

Tower with a double-helix spiral, adorned with letters of the Georgian alphabet.