Rock-hewn monastery complex with hundreds of cave structures tucked away into the mountainside.

Ancient rock-hewn town that witnessed key events of Georgian history.

An homage to the medieval rulers of Bulgaria.

A vast Communist-era exhibition space in the Bulgarian capital.

A magnificent, glittering building tucked into a tiny Bulgarian mountain town.

A gigantic statue of a Russian soldier watches over the ancient city of Plovdiv, a prominent reminder of the Soviet period in Bulgaria.

A mountain pass in Bulgaria's Balkan Mountains was the site of four historic battles.

This ancient theater, restored in the 20th century, lives on as a venue for dramatic and musical performances.

A striking symbol of the Bulgarian capital.

UNESCO-protected ancient burial ground.

Potato-peeling mannequins, Inca art, and a dangling tuber mobile help trace the history of fries at this Belgian museum.

Most prolific publishing house in the 1600s open to the public.

A magical and peaceful ruined Cistercian abbey in what is now southern Belgium.

This fairytale castle was built as a show of power but was nearly torn down thanks to its history of torture.

Climb inside an iron crystal magnified 165 billion times its normal size.

An abandoned saucer-shaped monument in the Bulgarian mountains.