This massive library holds what was once the largest book collection in the world.

This unassuming sculpture depicts grandfather of science fiction Jules Verne and his brother as children.

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

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

A museum dedicated to the former country.

A pair of connected skyscrapers form this symbolic gateway.

A Serbian church lit by chandeliers made of weapons.

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

An ornate private entrance to the Vienna subway built specifically for the emperor.

The housing complex served as an anti-fascist fortress during the Austrian Civil War.

Giant WWII fortresses that fired 8,000 rounds a minute, now home to thousands of pigeons.

This museum promotes informed contraception by documenting its often secret past.

Baroque celebration of the end of the Great Plague of Vienna.

The former private quarters and office of Dr. Sigmund Freud now hosts a museum housing the works of the founding father of psychoanalysis.

The beautiful baroque library of the Hapsburg empire.

The monument honors the mountaineers who were part of Europe’s best anti-Nazi forces.

A crumbling World War I fort that is reached through a series of concrete tunnels.

The "dragon babies" of southeastern Europe.

The walls of this medieval church are covered with perfectly preserved frescos, including a pristine example of the Dance of Death.

An otherworldly alpine pasture with its own unique microculture that recalls Middle Earth.

A monument to one of Croatia's famous freedom fighters.

A memorial dedicated to the 29,000 Istrian freedom fighters of World War II.

This unique structure allowed boats to bypass underwater mine barriers in the channel to enter the harbor.

Built as an anti-fascist tribute, this surreal Yugoslav memorial became an unwelcome symbol after the Croatian war for independence.