Site of one of World War I's most horrific scenes.

This ancient theater was once the home of fierce gladiatorial battles.

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

Beggars were miraculously "cured" of their fake ailments when they returned home to this 17th century Paris slum each night.

This surreal statue brings a famous French novel about a supernatural cad to arresting life.

A scandalous Art Nouveau collaboration that set Paris all atwitter at the turn of the century.

France's national museum of scientific and industrial instruments.

This massive library holds what was once the largest book collection in the world.

Paris' linguistic guide to the international language of, yes, love.

This former Imperial summer home was the venue for a royal slap that once echoed 'round the world.

Ancient serpentine sacrifice holder that has stood the test of time.

A fountain standing as a testament to a doomed alliance.

This remarkably well-preserved Egyptian plinth is pretty well traveled for a giant piece of stone.

1513 Turkish world map, full of European state secrets and snarky commentary.

A Turkish monastery tucked into a cliff wall.

A marvel of Byzantine engineering under the streets of Istanbul.

This small shrine is dedicated to the designer of the first Russian fighter jet and his brother, who became Chairman of the Presidium of the Supreme Soviet.

Nestled in a peaceful valley, this Armenian monastery may have been saved from Mongols thanks to the eyes of God.

The most visited pilgrimage site in Armenia once held a saint in a pit for 13 years.

Named after a legendary garden called Eram in southern Arabia, built by order of Shaddad, an Arab king who wanted to compete with Paradise.

Traditional 11th-century outdoor tannery.

Thousands of narrow alleyways in an ancient medieval city make up what's believed to be the world's largest car-free urban zone.

Crumbling necropolis set high above Fez.

The other side is actually green.