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

A narrow passage next to a cafe leads to a courtyard exploding with murals, tags, and paste-ups.

Carvings in Turkey's Marble Road may have directed ancient Romans to a hidden brothel.

A fountain standing as a testament to a doomed alliance.

The ancient latrines of the Greeks, in all their public glory.

The alleged house of the Virgin Mary is tucked away in a park and nature preserve on Mt. Koressos in Turkey and is holy to both Catholics and Muslims alike.

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

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

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

While not Turkey's deepest underground city, this subterranean redoubt is the largest.

The deepest underground city in Turkey was designed to protect 20,000 people behind massive stone doors.

This hunter-gatherer architecture is believed to be the oldest religious complex known.

A marvel of Byzantine engineering under the streets of Istanbul.

Roman ruins top white travertine terraces formed by ancient hot springs.

In this historic region, homes and churches are carved into ancient volcanic rock formations.

Now harmless, this looming post struck fear into the heart of medieval troublemakers.

The complex has been abandoned since the Croatian War of Independence, barring a stint as a set for 'Game of Thrones.'

A wunderkammer of gold and silver reliquaries and ancient saintly bones.

This scale model of our solar system hid in plain sight for years before a physics team sought out all the planets.

Longest fortress system anywhere in Europe.

This former estate of a fascist leader is now a burnt out ruin leading to a system of secret tunnels.

Gargoyle head that brings good luck.

Humble beginnings for one of the world's most famous scientists.

Where the lovelorn find a home for their sentimental keepsakes.