This 3,000-year-old “opium black fortress” towers over the ancient town named after it.

This 16th-century covered market is still open everyday.

A massive marble pedestal is all that remains of a column that towered over Constantinople for 1300 years.

The largest Neolithic ruins in the world hide a notably clean prehistoric metropolis.

A lush indoor jungle fills this bustling Madrid transportation hub.

View the ancient remains of buildings and the ancient "River of Hades" before hopping on a train.

These caves secretly held national treasures during World War II.

A Byzantine-era church hidden in a wooded area below the Acropolis.

Where commuters walk through remnants of an ancient Greek necropolis.

The ruins of an ancient Roman tomb hidden in the basement of a trendy clothing store.

Legend says this sacred tree was a gift from goddess Athena.

This ancient Greek place of assembly and marketplace is being revealed layer by layer below the modern Athens cityscape.

This abandoned shopping arcade has new life as an art installation.

The legendary wooden horse that stands in modern Troy is a prop from the 2004 Wolfgang Petersen film.

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

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

A unique and controversial artifact of the early Turkish Republic.

These falls, sometimes called the "Niagara of the West," still put on a good show at the right time of year.

The world’s first penitentiary, meant to be humane, drove men insane.

A well-worshipped shrine to the Virgin Mary nestled inside the last of Zagreb’s historic gates.

An eclectic art form practiced by untrained masters is celebrated at this museum in the heart of Zagreb's old Upper Town.

A hilltop fortress full of tombs, including one for legendary hero Seyyid Battal Gazi.

The oldest known standing wooden building in the world is a chamber inside a burial mound.

This harrowing memorial remembers a murdered investigative journalist.