One of the newest mosques in a city filled with thousands.

Climb a steep hill in 90 seconds on the second-oldest urban subway in the world.

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

A section of the long chain that blocked enemy ships from entering Constantinople.

A tiny park in the middle of some big power politics.

The legendary luxury train passage is commemorated with a charming museum inside its former eastern terminus.

A sixth-century Byzantine cistern hidden below a modern carpet store.

Five sultans and their families rest in eternal splendor, teeming with overlooked beauty and drama.

This crucial gathering spot along the "hippie trail" still displays old notes between traveling beatniks and backpackers.

This column celebrates Rome's victory over the Goths, and may be the oldest Roman monument in Istanbul.

Legend says if you stick your thumb in the hole and it gets wet, your wish will be granted.

A gorgeous, Gaudí-esque stairway constructed in the city of Istanbul by a prominent Jewish family.

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

No one is sure if the world's fourth-largest diamond had been found in a rubbish heap or was pawned by Napoleon's mom.

A marvel of Byzantine engineering under the streets of Istanbul.

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.

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

The silly symbol for an underground protest group is now scattered around the city.

Plaques celebrating Lithuanian writers freckle a wall of this picture-perfect path.

This abandoned coliseum was intended to be a grand Nazi rallying ground before it was halted at the end of the war.

The site of the famous Nazi book burning campaign of 1933 remembers its "Night of Shame".

This city square is home to Amsterdam's oldest church and a statue honoring Dutch sex workers.

A shining memorial to a Belgian hero is said to bring luck to anyone who touches it.