An expansive complex of subterranean tunnels is all that remains of one of Europe's most formidable medieval fortresses.

This magnificent museum claims to house the cranium of a disciple and the skull of a pope.

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

A rooftop restaurant hides in plain sight atop Vienna's Palace of Justice.

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

Dine amidst exotic plants at this former royal greenhouse.

The beautiful baroque library of the Hapsburg empire.

The crypt of the imposing Stephensdom holds royal intestines and thousands of skeletons.

A glimpse into the festive and private lives of medieval Europe.

The solemn exterior conceals an opulent interior of this 17th century church.

Visiting this café is like visiting the Austrian grandma you wish you had.

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

Along the edge of this fountain are 365 smaller fountains that represent the days of the year.

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

A neo-Gothic mansion now houses a wunderkammer of analog tech that hits on all the senses.

When a medieval fire claimed the original St. Stephen’s Cathedral, it sparked a pattern of unquenchable organ building.

Shimmering sea-colored mosaics and Jesus statues cover this opulent building.

In one of the world's smallest countries, a royal's personal winery is open to the public.

Archduke Ferdinand II's collection of rare objects is considered one of the oldest museums in the world.

Devilish masks, handicrafts, and pieces of old buildings create a snapshot of life in a historic Alpine region.

Terrifically morbid cemetary and site of famous Paracelsus' grave.

The world's largest historic armory was established by independent citizens to defend themselves from the wars of larger forces.

Austria's ultra-modern art museum looks like Cthulhu's giant alien heart.

Resting in the middle of an Austrian river, this sci-fi "island" lets people cross in neon style.