A spherical "micro-nation" in the heart of Vienna.

The crypt of the imposing Stephensdom holds royal intestines and thousands of skeletons.

The beautiful baroque library of the Hapsburg empire.

The metal leaves on this tree are engraved with the names of Holocaust victims.

This Hungarian castle was built out of cardboard and wood until it proved so popular that it got upgraded to stone.

Built in 1870 at the bridge that connected Buda and Pest, this spectacular incline railway was almost lost forever during World War II.

A trail of iron footwear stands as a monument to the thousands executed along this riverbank during WWII.

Also known as the Blue Church, the building was consecrated to the daughter of Andrew II.

This Slovak bridge is known both for its connection to a national uprising and its UFO-shaped eatery.

This Slovakian statue of an emerging sewer worker might just be a bronze peeping tom.

The old observatory in Copenhagen has a spiral corridor used as a racetrack.

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

Copenhagen's celebrated theme park and gardens.

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

This gem from the industrial age helps visitors and residents alike traverse hilly Stockholm.

Sweden's oldest animated sign is still lighting up the skyline today.

When this 18th-century observatory's meridian was moved, it set Sweden's time back by 0.04 seconds.

Stockholm's deepest subway station is also a stunning ecological wonder.

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

Stockholm's decidedly unique public transit system has doubled as the world's longest art gallery for decades.

A monument to the three wars that led to German unification towers within a Berlin traffic circle.

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

A restaurant and observation deck built in a unique broadcasting antenna.

Calcium-rich water has turned the water and rocks of these Philippines falls slightly green.