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

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

Heralded as the world's first theater, these ruins are often overlooked as they reside in the shadows of the Acropolis.

Elaborate stone houses constructed from the ruins of war.

The hallucinogenic center of the ancient world.

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

This historic black and white monastery is one of Bulgaria's architectural jewels.

This tiny Bulgarian town offers a stunning location in the mountains and a storied history.

Dedicated to the god Dionysus, this theatre was used for both musical and theatrical performances.

This architecturally eclectic early-20th century mosque was built as a place of worship for the Islamic followers of a Jewish messiah.

One of the most photographed locations in the entire city.

Turkish adventurer antiques in the heart of the Grand Bazaar.

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

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

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

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

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

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

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

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

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

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.