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.

Climb a steep hill in 90 seconds on the second-oldest urban subway in the world.

This futuristic German television spire is actually the world's largest digital clock.

Twisted buildings adorn the banks of the Rhine river.

The patron of this extravagant Art Nouveau confection insisted that nothing less than a boat should project from its facade.

An electrical pylon under whose legs a normal gauge train can run.

Sofia's legislative center is continuously reinventing itself.

An homage to the medieval rulers of Bulgaria.

A vast Communist-era exhibition space in the Bulgarian capital.

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

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

A striking symbol of the Bulgarian capital.

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.

This exquisite, alienesque piece of Soviet architecture is being threatened by modern shopping malls.

A fortress built to pacify local uprising that had a stint as a Nazi concentration camp before becoming a five-star hotel.

This 1000 year old relic-filled cave monastery and UNESCO World Heritage Site also hosts an amazing micro-miniature museum.

The deepest metro station in the world.

One of the largest museums in Ukraine remembers the story of the German-Soviet War in iconic, brutalist style.

340-foot statue built to honour the Heroes of the Soviet Union.

A reconstructed medieval gateway that was the magnificent entrance to the capital city dating back to 1037.

Two gilded cherubs perched on a church bell tower have been reminding visitors of the finitude of life since 1760.

An ancient water supply dating back almost 500 years can still be found standing in East Sussex.