World's most expensive home.

Apartment complexes built into huge repurposed natural gas tanks.

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

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

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

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

The topiary maze at the Habsburg hunting lodge.

The final resting place for the remains of 143 Habsburg royalty.

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

A peculiar clock commemorates a historic victory won by ringing the noonday bell an hour early.

Europe's second largest ossuary wasn't discovered until 2001.

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

The largest bell in the world has been swinging high above a Cologne cathedral for almost a century.

Thousands of tourists and residents in Cologne affix "love padlocks" on the Hohenzollernbrücke Bridge to symbolize their affections.

A church filled with the bones of hundreds of virgins martyrs—or so they say.

A magnificent collection of imperial armor and weaponry.

Vienna's diversity-themed traffic lights were inspired by the Eurovision Song Contest.

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

Dine amidst exotic plants at this former royal greenhouse.

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

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

Largest illuminated advertisement sign in the world.

A 1,100-ton train fell through the floor in 1953. Workers got it patched up in just 72 hours.

The railway carts travelers to central Athens's highest peak, which offers stunning vistas of the city.