A misnamed well, with a deep dark past.

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

Destroyed Serbian army headquarters sits half crumbled in a largely revitalized Belgrade.

Nikola Tesla's ashes are held in a golden sphere, surrounded by his works.

Structure built from the skulls of vanquished foes.

These historic defenses ensured the city within would survive hundreds of years of occupations, sieges, and invasions.

Hundreds of thousands of concrete bunkers crowd Albania long after the fall of Communism.

An Albanian monument to the Communism that nearly crushed the country is now a crumbling wreck.

A naturally beautiful, seemingly bottomless deep blue spring.

A former bank seized as a sniper vantage point during the Bosnian War is now a secret graffiti art gallery.

This museum preserves the hand-dug tunnel that kept Sarajevo afloat during the Serbian siege.

The largest cave chamber in Britain—big enough to fit a whole cathedral inside.

A quirky house created entirely out of glass bottles combines a collector's spirit with an artist's flair.

A gigantic collection of teeny, tiny books.

A shrine of fire worship built on top of a natural flame.

The building's fluid, wavelike walls are a true feat of architectural ingenuity.

Home to nearly a third of the world's mud volcanoes, Azerbaijan is home to a messy, bubbling, and sometimes explosive landscape.

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

A cylinder monument with a spectacular vista commemorates a friendship that some say never existed.

Take respite inside this jaw-dropping church while climbing the volcano where Georgia's Prometheus was once chained.

Unusual building appears to be haphazardly built from randomly piled bricks.

The charmingly disheveled clock tower of Tbilisi's puppet theater.

A museum glorifying the life of Stalin, located in the city of his birth.

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