Foreign invaders almost left this lovely Caucasus palace alone—almost.

This grand Pakistani mausoleum can only be accessed via an almost 1,000 foot long alleyway.

A small museum in this border city displays the contraband art that has been stolen back from smugglers.

This impressively complicated radioastronomy research center was once a tool of Soviet spies.

A top secret Cold War bunker hidden beneath a Latvian spa facility is now open for tours.

Spend the night in 1920s Latvia in this historic recreation and movie set.

"There's nothing there," and other lies the KGB told us.

The secret cells in the basement of the KGB's Estonian "Grey House" have been preserved as a grim Cold War museum.

An 18th century wonder of the world, lost in WWII, re-created at the Catherine Palace.

Monastery, army base, and infamous Soviet Gulag in the far Russian north.

A decommissioned submarine base makes a great space for graffiti art.

A lovingly curated curio shop in which the taxidermy wear newspaper party hats, and peanut shells are spread across every surface.

A subterranean house of worship carved right out of the bedrock.

Architecturally stunning library serves as the hub of Finnish scholarly life and culture.

A Turkish monastery tucked into a cliff wall.

Ottoman-era houses lovingly preserved.

An autonomous republic of Orthodox monks.

This bazaar is one of the oldest in the Arabian world.

These Nubian pyramids are strange and unique, even by pyramid standards.

Massive stele returned to Ethiopia after 70 years in Rome.

An ancient Ethiopian cave church is endangered by the simple building of a road.

An Ethiopian "Jerusalem" featuring a church hewn out of a single rock.

Yemen's "Stone Palace" looks like it was carved right out of the tall stone column on which it is built.

Abandoned city hidden from the world by tropical forest and isolation on the coast of Kenya.