This adorable birdlike police box is designed based on a play on words.

Starship-temple contains 400 tons of drinking water and offers free Japanese lessons.

Fine dining in the bizarre world of Lewis Carroll.

A marvel of Byzantine engineering under the streets of Istanbul.

This former estate of a fascist leader is now a burnt out ruin leading to a system of secret tunnels.

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

The place where World War I began.

The abandoned "Red Star Train Graveyard" is the final rusting place for precious artifacts of train history.

A 19th century artistocrat's mansion, turned into a library, hidden in a modern library.

After the famous composer died in Paris, his sister snuck his heart out of the country to honor his wish that it be buried in their native country.

The blood-soaked ruins of the castle where the murderous Blood Countess was walled in alive.

These secluded and abandoned anti-aircraft defenses have become one the most scenic viewpoints in Barcelona.

Gaudí's famously flamboyant architectural style is on full display in this sprawling park and garden.

Barcelona's historic 19th-century sewers, whose foundations were laid in medieval times, are open to the public for exploring.

One of Antoni Gaudí's most classic buildings is well-known for its "dragon-back" design.

Church built on the site where the last tsar of Russia and his family were killed.

A stone marker and sculpture in the city of Riga stake a claim for the very first community Christmas tree.

A black cat protests the City Guild in Riga's Old Town.

A top secret Cold War bunker hidden beneath a Latvian spa facility is now open for tours.

At 72 feet below sea level, it's the lowest commercial airport in the world.

A former imperial sea-fortress and Soviet prison.

Disused seaplane hangar gets a second life as the jaw-dropping home of Estonia's museum of maritime history.

This abandoned Soviet circus is slowly being restored to its Communist-era glory.