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

An ancient octagonal weather station named for the eight Greek gods of wind.

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

This legendary city has been a tourist attraction for centuries.

A 2,000-year-old computer demonstrates remarkable engineering and astronomical precision.

The hallucinogenic center of the ancient world.

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

This Dresden church was purposely rebuilt Protestant after being demolished in World War II.

A restaurant and observation deck built in a unique broadcasting antenna.

Beneath the impressive baroque cathedral that rises from the center of Berlin lies the largest collection of Prussian royals in the world.

On the Spree bank, discover one of the last reminders of a symbolic wall that divided, and was torn down by the people.

Thousands of coffin-like pillars make up this controversial Holocaust memorial.

The most visited, and possibly most controversial, museum in Germany.

With over 10,000 lights, this engineering marvel lights up the city after dark.

At this rare mosque in Tbilisi, Sunni and Shia Muslims pray side by side.

Fortified homes of highland warriors that are still in use today.

A cluster of historic bathhouses built on the famed hot springs that gave the Georgian capital its name.

Take respite inside this jaw-dropping church while climbing the volcano where Georgia's Prometheus was once chained.

The charmingly disheveled clock tower of Tbilisi's puppet theater.

Ancient rock-hewn town that witnessed key events of Georgian history.

Underground monastery and fortress.

Immortalized by artists, this church incorporates a medieval lighthouse into its shoreside structure.

Historic medieval fortified city in southwest France.

These small, brass stones commemorate the first Roma victims of the Holocaust.