A historic observatory precariously perched at the "Top of Europe."

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

At night, bats patrol this magnificent 18th-century space in search of book-eating pests.

This fairy-tale, neo-Gothic church in the Azores is a world of magical realism.

A 16th century chapel decorated with bones, skulls, and entire bodies hanging from the wall.

Walk 2,300 feet above the ground on the "Troll's Tongue."

Explore the art and history of intricate, hand-crafted tile designs at this small museum.

A cave dwelling that was started by the Celts, expanded by monks, and finished by knights.

A museum dedicated to a Cold War era sausage.

A charming and enigmatic sculpture of a lynx haunts the park of Kellinghusen.

An extraordinary mechanical calculator designed by the mathematician and philosopher Gottfried Leibniz.

A steam powered train that runs on city streets.

A small man-controlled waterfall powers an Art Nouveau elevator and is accessed via narrow gauge, solar-powered tramway.

A slice of central Asia in the middle of Berlin.

This hotel was once home to a steamliner company and became the final rest stop for Europeans heading to the New World.

This city square is home to Amsterdam's oldest church and a statue honoring Dutch sex workers.

Did he come up with a theory of cosmic-ray showers while sitting in this bath?

Over 9,000 brains collected between 1945 and 1982 demonstrate the results of untreated mental illness.

The traveling wares of Denmark's most famous author.

This museum is a portal to 20th-century Denmark.

The largest of Denmark's seven mysterious round churches stands on an island in the Baltic Sea.

The largest collection of hair jewelry in Europe reminds you how creepy 19th-century love was.

This striking royal residence is the largest Renaissance-style castle in Scandinavia.

The world's largest maze is a nature park with nearly 200 decision points.