A mysterious chasm in the heart of the ancient Roman Forum, the Lacus Curtius was once believed to be a gateway to hell.

Historic fortifications form the boundary of Vatican City, but it’s not entirely surrounded by walls.

This centuries-old tree tells an unusual tale of vegetation and fertility in the desert.

This 23-foot-tall bear stands amid the hustle and bustle of Hamad International Airport.

Sculptor Antony Gormley used chaos theory and fractal growth to design his tallest creation.

A museum dedicated to the former country.

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

A towering spire in the fortress of Kalemegdan honors the victorious armies of Serbia during their struggles against the Ottoman Empire.

Arguably Belgrade's only example of pure Art Deco architecture.

This unique museum focuses on the Siege of Sarajevo through children's eyes.

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

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

Inat Kuća, or "House of Spite," is more than just an oddly named restaurant.

Oriental bazaar in the heart of Sarajevo.

A number of craters left by fatal mortar strikes have been filled with red resin to remember those lost during the Siege of Sarajevo.

The first mosque in the world to receive electricity.

This historic timepiece is thought to be the only public clock in the world that keeps lunar time.

A monument on the pavement marks the spot where two cultures that shaped Sarajevo come together.

Bridge that died in war and was resurected.

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

This virtually windowless mass of smooth concrete is the only Catholic church in the city.

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

What happens when you cross a mayor and a painter?

A museum dedicated to secret surveillance.