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

This ancient hydrological marvel is now the base of a modern outdoor cinema.

Monasteries on rock pillars, once accessible only by frayed ropes.

A massive stairway that almost wasn't leads to one of Australia's most scenic vistas.

An ancient engraving by the Cammeraygal people was uncovered in the transformation of a North Sydney industrial site.

Peru's (not so) mysterious carved stones.

19th century museum with an eclectic mix of curiosities, from Egyptian artifacts to items on archery history to the skull of the world's oldest horse.

A Victorian Gothic masterpiece housing a world-class collection of rare books and manuscripts.

Known as the Hintz House, this medieval pharmacy has been an apothecary's haven for nearly 450 years.

A medieval military street hidden beneath a charming French fishing village.

The oldest cemetery of modern-day Athens blends the modern and ancient worlds.

The railway carts travelers to central Athens's highest peak, which offers stunning vistas of the city.

150 or so scrounged-up lamps, chandeliers, and lanterns light up this alley in central Athens.

A friendly monster lurks outside the State Library Victoria.

Occult books, tarot, oddities.

The labyrinthine storm tunnels beneath the city of Melbourne are ruled by a band of urban explorers.

Ruins of a late 1950s Polish ski jump ramp in the middle of the city.

A national collection of Communist-era musical posters.

Naturally formed rock city in Poland.

The walls and ceiling of this Polish church are decorated with thousands of skulls, with another 21,000 skeletons just below.

The intricate stonework of Machu Picchu serves as a testament to Incan engineers.

This jaw-dropping 19th-century bridge uses its reflection to form what appears to be a perfect circle.

One of the few remaining casualties of the London Blitz, this destroyed church has become an enchanting public garden.

Tucked in the back of this amazing antique store is an important piece of medical history.