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.

Visitors dip into a variety of pools of what was once ice.

Apartment complexes built into huge repurposed natural gas tanks.

Dine amidst exotic plants at this former royal greenhouse.

Each year melting snow turns these Austrian hiking trails into scuba zones.

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

Op-art architecture designed for happiness.

Where beer lovers can literally immerse themselves in beer.

The topiary maze at the Habsburg hunting lodge.

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

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

A dream-like maze full of strange art, surreal spaces, and fantasy landscapes to get lost in.

This historical Netherlands fortress still bears the marks of its single siege.

Survival capsules find a second life as a unique hotel.

This miniature take on the Kremlin is one Dutch man's retirement project.

A grassy pyramid named after a French battle.

This museum inside Amsterdam's largest cemetery explores how people deal with death.

The ruins of this Dutch castle sit atop a labyrinth of once-secret tunnels and passageways, dating back over 900 years.

This centuries-old gothic monster has been converted into a sprawling, glossy bookstore.

Unsurprisingly, Holland is home to one of the most magnificent flower gardens in the world.

Invisible bridge parts the waters, invoking biblical images and preserving the ominous feel of an ancient moat.

This 22-floor tower's Skydeck offers panoramic views of Amsterdam.

A beautiful maze marks where three countries meet.