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

This massive subterranean fissure is known as the "underground Grand Canyon."

Castle and secret tunnel withstood a siege until its owner was killed by the Holy Roman Empire, while sitting on the toilet.

The “world’s smallest cathedral” is a remnant of one of Croatia’s medieval royal towns.

Picturesque basketball courts sheltered by historical defensive walls and with an enviable sea view.

Longest fortress system anywhere in Europe.

One of the best-preserved Roman amphitheaters is still used today, but for less brutal events.

A chain of 16 wondrous lakes formed as a result of the gradual dissolution of soluble layers of bedrock.

These historic defenses ensured the city within would survive hundreds of years of occupations, sieges, and invasions.

A tiny church on a man-made island in the Adriatic.

This exclusive resort has completely covered a tiny Balkan island in a 5-star warren of guest rooms.

A memorial to the atrocities of the People's Socialist Republic of Albania.

Gigantic water vessel, permanently grounded in Southern Albania.

A scenic UNESCO site that doubles as a habitat for various forms of wildlife.

In the heart of Tirana, this underground nuclear bunker has been transformed into a museum.

What happens when you cross a mayor and a painter?

Hundreds of thousands of concrete bunkers crowd Albania long after the fall of Communism.

An Albanian monument to the Communism that nearly crushed the country is now a crumbling wreck.

When you enter this complex it is like walking onto a Sci-Fi film set.

This medieval synagogue survived the Inquisition as a hospital and church.

Walk into an underground archeological dig, the site of the Roman Forum that was once the center of Valencia.

The Roman city was the birthplace of various emperors and is home to one of the empire's most impressive architectural feats.

Spain's unique Mosque-Cathedral has been a place of worship for both Muslims and Christians throughout its history.

Spanish architects used seized Muslim gravestones to rebuild parts of the fortress.