This giant boulder is pinched over a 1000-meter abyss by two mountains.

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

The world's northernmost brewery uses water from a 2,000-year-old glacier to create its beer.

The world's largest underwater restaurant is submerged off the southern tip of Norway.

A Viking-style brewpub named for a Norse sea giant, in the heart of fjord country.

The only natural cave bath in all of Europe.

This pair of unsuspecting buildings are in fact the very first modern skyscrapers in Europe.

A cenote sitting in the middle of a parking lot shows the Yucatán Peninsula at its most urbanized.

A World War II torpedo launch station abandoned off the Polish coast.

Once a safe haven for locals engaged in blood feuds, this 400-year-old fortified tower is now a museum showing what life was like for those lying in wait within its walls.

A UNESCO-protected spiritual seat of the Old Serbian Kingdom and Empire.

Perhaps the only one of its kind, the nearly-forgotten site once held mortal (and rigged) gladiatorial games between tigers and imperial war elephants.

One of the oldest structures in Helsinki is this burrow grave that dates back to the Bronze Age.

Visit a secretive crypt before it crumbles to dust.

This formerly-prosperous Silesian mining town was completely demolished in the late 1960s and early 1970s as an attempt to cover up a secret Soviet uranium mine.

Hidden underground, a remarkable 10th-century bath complex survives virtually unaltered.

An extensive network of secret tunnels was created for the Nazi project "Riese."

This unique museum focuses on the Siege of Sarajevo through children's eyes.

A uniquely preserved neo-Gothic church that is now home to a collection of art and woodcarvings.

This cozy café is housed in a repurposed pharmacy originally built in 1927.

For more than 170 years, this family-run bakery has been serving Berlin’s best Baumkuchen, or “tree cake.”

Visit an imposing 13th-century Transylvanian fortress lurking not far from the region's more heavily touristed attractions.

A museum specifically dedicated to the Trabant, one of the iconic automobiles of the GDR.

A tribute shrine where the Space Invasion street art movement started.