These numerous Israeli caves were dug out over hundreds years for reasons ranging from hideouts to burial sites.

Relics from an era long gone, sit idle outside this Estonian museum.

The oldest continuously operating pharmacy in Europe.

This medieval Estonian tower provides access to a series of tunnels that have been home to soldiers, punks, and fine art.

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

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

This architecturally eclectic fortress witnessed centuries of bloody turmoil, including the massacre of its ruling clan.

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

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

Rock-hewn monastery complex with hundreds of cave structures tucked away into the mountainside.

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.

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

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

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.

This museum holds the most comprehensive collection of Armenian art in the world.

Huge stairway leads to this massive gallery.

This medieval manuscript collection has some of the most obscure and ancient texts in the world.

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

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

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

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