From Austrians to Nazis to Soviets, this historic Budapest fortress has a history as complex as the city itself.

Built in 1870 at the bridge that connected Buda and Pest, this spectacular incline railway was almost lost forever during World War II.

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

This Hungarian castle was built out of cardboard and wood until it proved so popular that it got upgraded to stone.

A serious museum dedicated to two German comedians.

Daily jousts and dancing barrel makers in Munich's mechanical clock.

Pilgrimage site for star-crossed lovers.

Milan's duomo is covered in beautiful carving including a curious "dinosaur-like" beast.

Two very green residential towers cleaning the air in one of Europe's most polluted cities.

Rock carving created 1,300 years ago 75 feet off the ground.

This tiny Bulgarian town offers a stunning location in the mountains and a storied history.

"Holy Wisdom" overlooks the city that became its namesake.

Sofia's legislative center is continuously reinventing itself.

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.

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

A flamboyant five-story building in Bulgaria resembles a crawling snail.

"Unity, Creativity, Beauty."

Ruins of an early Roman Christian church dating back to the 4th to 5th centuries.

An homage to the medieval rulers of Bulgaria.

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

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

A mountain pass in Bulgaria's Balkan Mountains was the site of four historic battles.

A magnificent, glittering building tucked into a tiny Bulgarian mountain town.