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

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

This 3,800-year-old site contains markers used to study the movement of the sun and moon and create a lunar calendar.

Space-age monument to an early 20th-century uprising.

The house that took a plunge into the facade of a museum.

Dine amidst exotic plants at this former royal greenhouse.

This series of Baroque passageways in Vienna's cultural center mix old architecture with modern art.

On a winding Vienna side street, one museum has turned their windows into a monument to history’s peace-minded heroes.

Apartment complexes built into huge repurposed natural gas tanks.

A neo-Gothic church built to thank God for saving the Emperor of Austria from an assassination.

A silly medieval mural preserved on the side of a Viennese house.

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

Vienna's giant wonder wheel had a starring role in one of the greatest noir movies of all time.

Legends surround an ancient tree trunk riddled with nails for good luck.

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

Beautiful Austrian natural history museum with carved ceilings and row after row of ancient taxidermy.

Op-art architecture designed for happiness.

This cubist Vienna church building looks like some sort of alien stonehenge.

Located right outside of Vienna, visitors can take in expansive views of an ethereal forest.

A spherical "micro-nation" in the heart of Vienna.

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

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

A tropical paradise just a short trip from the opera house is filled with beautiful winged creatures.

The beautiful baroque library of the Hapsburg empire.