An Art Nouveau gem hides beneath the layers of city grime obscuring this once-magnificent building.

Gladiators battle and chariots race daily in the ruins of a once-great Roman city.

This flagpole ranks among the world’s tallest and can be seen from three countries.

An ancient capital city that dates back 3,000 years and harbors many surprises.

Balanced on four stone pillars, this historic tower was the site of a tragic political assassination.

An Ethiopian "Jerusalem" featuring a church hewn out of a single rock.

Ottoman-era houses lovingly preserved.

Resting place and mausoleum of the founder and first president of Turkey.

Sanctuary on a ridge near an ancient shrine to a "Black Madonna" built by the founder of Opus Dei.

A site where “the ravages of the war are more striking…than any other place in contemporary Spain.”

A spectacular rainbow of stained glass makes the "Pink Mosque" one of the most beautiful in Iran.

Mirrors and glass shards cover every inch of this arrestingly beautiful mosque.

A dreamy mausoleum honors Persia's most famous poet.

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

Modern-day cave dwellers carve elaborate homes out of volcanic debris.

The largest covered bazaar in the world.

In this tiny Iranian town playing on the roof isn't just encouraged, it's the only place to go.

This peaceful Sikh gurudwara serves around 50,000 free meals every day within its gilded walls.

An ocean in the making, in the Ethiopian desert.

A salt lake dotted with steaming limestone chimneys.

Rimmed by white crusts of salt on every edge, Lac Assal is one of the saltiest bodies of water in the world.

This tiny river island switches sovereignty every six months as part of a rare, centuries-old agreement.

A Turkish monastery tucked into a cliff wall.

An abused and forgotten metropolis, abandoned for centuries.