One of Jeff Koons’s largest sculptures and his first commemorative work.

The Argonaute submarine was the French navy's pride and joy in the 1950's.

This bridge was constructed from the rubble of the infamous Bastille.

High atop the Eiffel Tower is a small apartment built exclusively to entertain the science elite and make the rest of Paris jealous.

A giant portrait of an ancient king looms over the river.

A pair of connected skyscrapers form this symbolic gateway.

This modern museum of Mediterranean culture is surrounded by a surreal concrete honeycomb.

Even France's favorite aquatic son Jacques Cousteau, couldn't get to the bottom of it.

Sofia's legislative center is continuously reinventing itself.

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

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

"Holy Wisdom" overlooks the city that became its namesake.

"Unity, Creativity, Beauty."

Eastern Bloc nostalgia, anybody?

Rock carving created 1,300 years ago 75 feet off the ground.

A striking symbol of the Bulgarian capital.

Mysterious standing stone formations looks like a petrified forest.

The remarkably well-preserved final resting place of a powerful ancient Thracian king.

This once-grandiose behemoth of a monument from the socialist era now sits quiet and closed up.

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

The second-largest Jewish temple in Bulgaria was deserted after World War II, seized by the communist government and then abandoned again.

The site of many battles and tragedies, including the 40 maidens who leapt into the sea.

This historic black and white monastery is one of Bulgaria's architectural jewels.

This massive concrete sculpture is said to be the heaviest communist monument on Earth.