What looks like a crashed Zeppelin is actually a bright, airy reading room perched atop a modern museum.

Two stunning 17th-century libraries and a cabinet of curiosities.

An abandoned brutalist monument whose history has been lost to the ages.

This doorless 20th-century elevator doesn't stop or slow down.

A bust of Franz Kafka spins in pieces, reflecting the writer's inner torment.

The last municipal pneumatic post system in the world was in operation for over 100 years, and may run again.

A mocking tribute to the past and modern leadership of Prague.

Yugoslavia's biggest underground airport lies in ruins.

This spire on an Austrian mountain is wrapped around a long spiral slide and has the world's tallest wooden observation deck.

This brutalist monument is inscribed with 9921 names of Yugoslav partisans who perished during WWII.

This huge metal monument is slowly being stripped to its concrete skeleton.

Croatia's towering concrete blossom grows from the site of a World War II concentration camp.

This stunning, out-of-the-way Croatian monument commemorates a community's uprising against occupying fascist forces.

The world's largest collection of intentionally useless inventions.

This former insane asylum now holds a pathological anatomy museum.

The former private quarters and office of Dr. Sigmund Freud now hosts a museum housing the works of the founding father of psychoanalysis.

The beautiful baroque library of the Hapsburg empire.

A tropical paradise just a short trip from the opera house is filled with beautiful winged creatures.

Vienna's underworld of tunnels and subterranean rivers made an iconic appearance in a 1949 Orson Welles film.

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

This Budapest bar allows drinkers to leave their mark on the walls, floor, and even ceiling.

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

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

This Austrian museum celebrates the work of famous forgers and their inimitable imitations.