Tower with a double-helix spiral, adorned with letters of the Georgian alphabet.

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

A gleaming white and undulating tower marks the border between Georgia and Turkey.

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

A museum glorifying the life of Stalin, located in the city of his birth.

A cylinder monument with a spectacular vista commemorates a friendship that some say never existed.

Unusual building appears to be haphazardly built from randomly piled bricks.

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

The first skyscraper to include a Ferris wheel built into the facade.

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

Underground monastery and fortress.

Ancient serpentine sacrifice holder that has stood the test of time.

A Turkish monastery tucked into a cliff wall.

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

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

This famous city eluded concrete detection until the early 2000's.

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.

This hauntingly beautiful cemetery outside a medieval citadel is full of winding paths and ivy-covered graves.

One of the most controversial statues in Romania is an emperor with no clothes.

Nine centuries-old fortresses guard the walls of this medieval Romanian city.

This communist behemoth is the heaviest building in the world and a legacy of a brutal regime.

A fire once nearly devoured this gorgeous 14th-century Gothic cathedral.