Op-art architecture designed for happiness.

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

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.

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

This former insane asylum now holds a pathological anatomy museum.

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

Hidden beneath the famous St. Peter's Basilica is a veritable city of the dead that may hold the remains of St. Peter himself.

The famous sculptor left his mark on this Italian wall in an internationally protected example of street art.

The fading, forgotten remains of a once bright and booming factory.

A new sculpture calls attention to climate change in the centuries-old city it threatens.

The marble facade hides a little-known medical museum with early surgical instruments and rare copies of canonical texts.

Thousand-year-old Viking runes adorn an ancient Greek lion at the entrance to the Venetian Arsenal.

Shop for books in the New Orleans house where William Faulkner once lived.

By day this New Orleans square is for pedestrians, but by night it is a kingdom of kittens.

This knobby, drooping New Orleans oak is a favorite place both for climbing and for meeting giraffes.

This New Orleans tree is filled with hidden chimes that produce a carefully tuned melody.

A collection of oddities including Dr. Kevorkian's suicide device, the Thanatron.

A snapshot of the city's fascinating voodoo culture.

Enchanting cave with a river crashing through the roof.

Bolivia's needle-like rock formations.

An abandoned tuberculosis hospital said to be haunted by the patients who died within its walls.

This 15th century pharmacy displays a beautiful collection of ancient medicine jars.

Trek into the depths of the cave where 17,000-year-old paintings exist alongside 400-year-old graffiti.