Berlin's old airport.

This World War II bunker now survives as a documentation of the Nazi regime and war crimes.

An abandoned NSA listening post on Berlin's "Devil's Mountain."

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

An eerie, derelict amusement park in Berlin.

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

Construction of Barcelona's iconic (but controversial) church is expected to be completed in 2026—a century after the death of its architect.

This museum housed in a former brothel explores the past and present of sex work in Amsterdam.

A Dutch passageway's artistic, aquatic-themed makeover pays tribute to the capital city's famed waterways.

One of Indonesia's tallest, this waterfall takes a 390-foot plunge into the Lake Toba caldera.

The unique funeral practices of the Toraja can be seen here with graves carved into caves and hung off cliffs.

This sacred cave temple is home to thousands of bats and according to legend, a giant snake king.

One native village in Bali lays their dead at the foot of a holy tree whose natural fragrance seems to hide the stench as the bodies decompose.

Hindu temple of the dead home to hundreds of long-tailed macaques.

The name of this ancient Indonesian temple translates as "Elephant Cave" but it could be more accurately called "The Hellmouth."

Bali's remote "gateway to heaven" is one of the most sacred places on the island.

This Balinese sea temple is thought to be guarded by the hundreds of monkeys that live around it.

Walk inside a half mile long crevice right outside the town of Garmisch Partenkirchen.

Dress up like a miner and take a slide into the disco-lit depths of this once foundational salt mine.

There has been an astronomical clock on this spot since the 14th century.

One of the most well-preserved castles in Italy also contains a rare medieval example of a port fortification.

Visitors dip into a variety of pools of what was once ice.

Three bridges and one giant canyon make up this fantastic Spanish settlement.

Spanish architects used seized Muslim gravestones to rebuild parts of the fortress.