Built to give thanks for the passing of a plague epidemic, this cathedral is a one-of-a-kind architectural hybrid.

Apartment complexes built into huge repurposed natural gas tanks.

In the middle of a Vienna square, Roman ruins dating back some 2,000 years are on display.

A NATO bombing took the lives of 16 civilians in 1999—the ruins remain in the center of Belgrade.

Memorial to the 89 children killed during the NATO bombing of Serbia.

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

This feat of Brutalist architecture is also known as the Three Sisters.

A museum dedicated to the former country.

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

This striking, historic hotel has major Wes Anderson movie energy.

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.

One of Belgrade's most beloved animals.

Former military fort and site of untold horrors during WWII, this island may become the Adriatic's next luxury resort.

The mark of the Devil's horns on a marble column in Milan.

The most impressive of Basel's three remaining city gates.

An unassuming Swiss institution houses Europe's largest toy museum.

This ferry carries passengers across the Rhine propelled by no engine or paddles but by the river's current.

The smallest museum in Basel, Switzerland, is a two-foot-by-two-foot window in the door of a 600-year-old house.

This artistic fountain display pays homage to this area's theatrical history.

This 42-foot tribute to the workforce still reminds us to pause and recharge.

On top of a resort town as old as the Bronze Age sits an incredible war memorial statue overlooking the beaches below.

One of the world's oldest olive trees, thought to be over 2,000 years old.

A monument on the pavement marks the spot where two cultures that shaped Sarajevo come together.