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

Legends surround an ancient tree trunk riddled with nails for good luck.

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

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

A former 16th-century monastery houses a museum dedicated to the island and its culture.

The largest salt farm in the Canary Islands is located at the foot of an active volcano.

This mountaintop observatory is home to one of the world's largest reflective telescopes.

Indigenous cultures believed all life would end if this enormous rock toppled.

The oldest Marian image in the Canary Islands still impresses people nearly half a millennium later.

These wooden balconies that are both decorative and functional.

Volcanic rocks ground down into sand make this Spanish beach as black as night.

Behind medieval walls in a corner of bustling Palermo is a breathtaking former mosque once inhabited by a wolf-taming hermit.

Thousands of well-dressed mummies below a monastery.

"Stairs of the Turks", a chalky white cliff eroded conveniently into stairs, allowing for easy pillaging.

A madman's personal garden filled with 1,000 sculpted heads.

Italian cave with exceptional acoustics and an unsavory history.

For part of the year, this innovative greenhouse is painted white to keep the plants from getting scorched.

The only monument to name all of the passengers and crew who died on the RMS Titanic.

This massive monument has been telling the time for 150 years—at a slight angle.

A giant sculpture of the legendary "Salmon of Knowledge" celebrates the return of fish to Belfast's River Lagan.

These engineering masterpieces are a dominant feature of the Belfast skyline.

The ship built to ferry passengers and goods to the doomed Titanic is now the last remaining White Star Line vessel.

A museum marks and documents the site of the Titanic's launch.

The atmospheric road was never meant to be so creepy.