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

Op-art architecture designed for happiness.

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.

The topiary maze at the Habsburg hunting lodge.

This former insane asylum now holds a pathological anatomy museum.

Handsomely crafted representations of our round planet.

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.

A small museum filled with over 1,000 clocks, and one particular clock calibrated to run until the year 9999.

The medieval network of canals hidden underneath the city is opened to explorers each year.

Trick water gardens from 1619 featuring a 200 piece mechanical theater powered by water.

This Catskills museum preserves stumps from the earliest known fossil forest on Earth.

Castle and secret tunnel withstood a siege until its owner was killed by the Holy Roman Empire, while sitting on the toilet.

A fantastical 13th-century fortification sandwiched by a modern hotel in central Brussels.

Theme park featuring miniature replicas of European monuments.

This modern arts center is built around a gem of late-Baroque architecture.

Lavish royal estate punctuated with heated greenhouses.

Climb inside an iron crystal magnified 165 billion times its normal size.

Cozy basement bar sports an inventory of over 2,000 beers.

Three floors of musical instruments coming from all corners of the world and hundreds of years of musical history.

Frida Kahlo's childhood home, now a museum of her life and works.

In this mine all the gold you can carry may not be as sweet of a deal as it sounds.