A huge communist-era propaganda monument and mural that offers stunning views of the Mongolian capital.

Intricate wood carvings on an island in Siberia.

Former headquarters of the KGB.

World's largest bell sits on the grounds of the Kremlin in Moscow.

This building holds the embalmed remains of the leader of the Bolshevik Revolution.

A 250-year-old timepiece-automaton adorned with golden mechanical birds, which still sing to this day.

This cluster of little wooden huts once ground local farmers’ wheat into flour during the days of the Austro-Hungarian Empire.

Serbia's master of striking memorials erected a forgotten, hidden gem in the hills outside a tiny village.

A radio telescope for listening to the stars, based in one of the cloudiest countries in the world.

Go inside a revolutionary, cage-less zoo where 70 species of monkeys roam free alongside their human visitors.

A war-torn Olympic relic is being overtaken by graffiti and nature.

A curious cave church carved into the face of a cliff.

Structure built from the skulls of vanquished foes.

Bridge that died in war and was resurected.

A Red Cross memorial museum at the site of the Niš concentration camp that operated for four eventful years during World War II.

This brutalist monument is inscribed with 9921 names of Yugoslav partisans who perished during WWII.

An abandoned saucer-shaped monument in the Bulgarian mountains.

These warring psychedelic crags commemorate an unsuccessful military operation.

This memorial park stands on the site of one of the largest mass executions of the Second World War.

This disused VLF radio station is no longer in service but the surrounding town still bears its name.

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

Swarms of dainty flying insects swarm into the Petaloudes Valley to get busy.

Pilgrimage site for star-crossed lovers.

Go inside to really appreciate this 500-year-old technological masterpiece.