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

This half-forgotten fortress was constructed by the Ottoman conqueror of Constantinople.

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

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

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

One of the largest wooden constructions in Europe was meant to be a casino, but soon became an orphanage.

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

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

A fountain standing as a testament to a doomed alliance.

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

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

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

Large miniature theme park with 100-plus models.

The most metal church of all time was built in record time because of an international, pious pissing contest.

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

This museum was invented in a novel before being made real by the author.

Step back in time and witness the fall of Constantinople.

A marvel of Byzantine engineering under the streets of Istanbul.

The ornate miniature mansions were built for Istanbul's feathered residents.

A small etching on the white marble parapet was written in runic script by a Viking mercenary.

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

Taking the subway here means doing so over a bridge located in the middle of an estuary.

A surprising and unconventional mosque hidden in the subsoil of Istanbul.