Centuries before the modern seismograph, Armenian monks measured quakes with this tilting pillar.

After visiting hours, this picturesque waterfall is essentially turned "off" to be used for hydroelectric power.

When the Soviets destroyed the historic Armenian monastery they somehow left its bell tower intact.

Hidden up a dusty track off the Georgian Military Road is this fascinating waterfall with mountainous views.

A Spanish town built into the cliffs.

A spectacular Petrine Baroque summer palace commissioned for Catherine I by Peter the Great.

The widest natural waterfall in Estonia is a sight to see in all seasons.

This stunning limestone waterfall is the highest in Estonia.

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

A decommissioned submarine base makes a great space for graffiti art.

An empty relic of the Moscow Olympics crumbles away in Estonia's capital.

A striking symbol of the Bulgarian capital.

A Bulgarian monument to Russia's role in World War II is constantly being painted in pop culture protest.

A collection of art from Bulgaria's time as a communist state.

"Unity, Creativity, Beauty."

This massive concrete sculpture is said to be the heaviest communist monument on Earth.

The ceiling of Prohodna Cave in northern Bulgaria affords a peek at the sky via two deity-sized-eye-shaped holes.

A gigantic statue of a Russian soldier watches over the ancient city of Plovdiv, a prominent reminder of the Soviet period in Bulgaria.

This ancient theater, restored in the 20th century, lives on as a venue for dramatic and musical performances.

A massive cave once a secret military base is now home to thousands of bats.

A decaying, yet still functioning, work of communist architecture.

This massive stone and steel monument remembers a century-old battle that cost thousands of lives and nearly destroyed the city.

An abandoned saucer-shaped monument in the Bulgarian mountains.

A single light illuminates one man's overshadowed contributions to street lamp history.