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

An abandoned Byzantine fortress and notorious prison.

This gem is often wrongly overshadowed by the larger, newer Metropolis church in Athens.

Where commuters walk through remnants of an ancient Greek necropolis.

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.

This legendary city has been a tourist attraction for centuries.

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

The hallucinogenic center of the ancient world.

Hundreds of intricately carved Armenian stone crosses can be found within this huge cemetery.

Nestled in a peaceful valley, this Armenian monastery may have been saved from Mongols thanks to the eyes of God.

This ancient monastery complex was transformed from an island to a peninsula when the lake was partially drained.

The most visited pilgrimage site in Armenia once held a saint in a pit for 13 years.

This Armenian monastery was carved out of cliffs and named after the spear used to stab Jesus.

A geological oddity topped with a 2,000-year-old pagan temple.

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

A small but hugely whimsical theater where marionettes play out the "The Battle of Stalingrad."

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

You'll find just about anything in this funky Tbilisi flea market.

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

Underground monastery and fortress.

This home designed for chocolate magnate Antoni Amatller is an exquisite treasure-box of Catalan Modernism.

This stunning iron gate designed by Modernist architect Antoni Gaudí is filled with mythic symbolism.

The oldest giants in Catalonia are now displayed in a 14th-century Gothic church.