A Black Forest cuckoo clock theme park features one timepiece big enough to walk inside.

In addition to fine dairy products, the world's most beautiful milk shop also offers a feast for the eyes.

The prototype for all Nazi concentration camps.

No need to strap in for a “ride” on this walkable roller coaster.

Soaring over 6,000 feet in the Bavarian Alps, this beer garden was once Hitler's 50th birthday present.

A striking 12th-century-style castle built on the edge of a cliff.

A sprawling Baroque park with 300-year-old hydro-pneumatic waterworks.

This medieval castle overlooking the Elzbach river looks just like it did hundreds of years ago.

Thousands of coffin-like pillars make up this controversial Holocaust memorial.

The fairy tale castle of the “fairy-tale king,” this was also the inspiration for Disney’s “Sleeping Beauty.”

This jaw-dropping 19th-century bridge uses its reflection to form what appears to be a perfect circle.

This building, previously used as a courthouse, has an unusual geological feature in its basement.

A small church in Uppsala hides the grave of a renowned 18th-century astronomer.

Sweden's largest optical telescope sits on a rooftop in Stockholm.

This fantastic cave remained unexplored until 1948 when three schoolboys discovered a hidden entrance.

The 19th-century home of Count and Countess von Hallwyl is now a museum.

Although rarely used, there is still a hidden room for the royal family at the Stockholm central station.

Sound travels strangely in this underground whispering gallery.

This small museum nestled inside a souvenir shop is dedicated to Sweden's most well-known toy.

One of the world's few mounted blue whales, its jaws are hinged open allowing visitors to descend into a lounge.

The remains of Alfred Nobel's first nitroglycerine factory can still be found on the shores of a Swedish bay.

One of the most spectacular bridges in Spain spans a narrow chasm that divides the city of Ronda.

A Spanish town built into the cliffs.

The silly symbol for an underground protest group is now scattered around the city.