Peek into a cave of giant, glimmering crystals.

Despite its grandiose name, this enigmatic first-century void under the town is no cave, and it's possibly not a palace either.

The 14th-century ruins are said to contain healing powers.

The soulless eyes of 82 bronze children stare on forever in remembrance of a horrifying World War II massacre.

Created as a "model concentration camp" to hide Nazi atrocities from the international community, this former camp-ghetto now holds a museum and memorial honoring the lives lost within.

Underneath this small church are 15,000 bones, arranged by an obsessive academic.

Two monstrous faces loom over a village in Czechia.

A little-known cafe in an old copper bridge tower with 360-degree views of the harbor.

The largest bottled beer collection in the world holds over 22,000 unique beer bottles.

Hans Christian Andersen for the postmodern world.

This collection of over 50 murals celebrates Brussels' rich history as the self-proclaimed home of the "comic strip."

This Russian diner is staffed entirely by twins.

This small museum is basically a time capsule of daily life in the Soviet Union.

One of the last examples of Soviet architectural propaganda has a few technological tricks up its sleeve.

The world's first museum dedicated to the work of game-changing naturalist Charles Darwin.

Moscow's most popular cemetery includes the graves of numerous cosmonauts.

It took over half a century but a Russian monument to a famous and tragic space pup finally stands in Moscow.

The gorgeous entrances into the city's underbelly look more like grand halls than subway stops.

Thirteen sculptures in central Moscow graphically depicting vices of the modern world.

An early-20th-century "dacha" village of quaint cottages curiously located in a modern part of Moscow.