The sister plane of the C-123 shot down during the Iran-Contra Affair has found a new purpose in retirement.

A 1,215-foot tunnel transports pedestrians beneath the River Thames.

One of England's most famous churches hides a pair of little known architectural treasures.

One of the few standing Roman lighthouses and a labyrinth of tunnels are a couple of the secrets at this historic castle.

Climb inside an iron crystal magnified 165 billion times its normal size.

This fairytale castle was built as a show of power but was nearly torn down thanks to its history of torture.

This one-time health resort was used by aristocrats around the world.

A whimsical bridge adorned with decorative dragons.

This abandoned Slovenian military barracks has become a punky-political art squat.

This Slovak bridge is known both for its connection to a national uprising and its UFO-shaped eatery.

A trail of iron footwear stands as a monument to the thousands executed along this riverbank during WWII.

Destroyed Serbian army headquarters sits half crumbled in a largely revitalized Belgrade.

Nikola Tesla's ashes are held in a golden sphere, surrounded by his works.

A misnamed well, with a deep dark past.

A towering spire in the fortress of Kalemegdan honors the victorious armies of Serbia during their struggles against the Ottoman Empire.

A giant portrait of an ancient king looms over the river.

This historic black and white monastery is one of Bulgaria's architectural jewels.

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

Romania's triumphal arch looks out over Bucharest.

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

An abandoned saucer-shaped monument in the Bulgarian mountains.

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

Luxury hotel turned into a refugee camp, then turned back into a luxury hotel.

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