The caldera of this mini-volcano has been turned into a naturally heated mud bath.

This elegant Colombian fortress was one of the torture headquarters for the Spanish Inquisition.

Every equinox this Maya pyramid puts on a spooky ancient light show.

A black cat protests the City Guild in Riga's Old Town.

Flamboyant architecture from the turn of 20th century.

Medical museum that houses most notably the taxidermied remains of Vladimir Demikhov's famous two-headed dog experiment.

The Guardian of Tallinn.

An empty relic of the Moscow Olympics crumbles away in Estonia's capital.

An 18th century wonder of the world, lost in WWII, re-created at the Catherine Palace.

A 250-year-old timepiece-automaton adorned with golden mechanical birds, which still sing to this day.

Palace where the nearly un-killable Rasputin was murdered.

This insurance company building reminds customers that witches, bears, and gnomes are out there, best be insured.

A subterranean house of worship carved right out of the bedrock.

Architecturally stunning library serves as the hub of Finnish scholarly life and culture.

Early habitat dioramas and home of the elusive gaff, the skvader.

Stockholm's decidedly unique public transit system has doubled as the world's longest art gallery for decades.

The only structure left with direct ties to the Salem witchcraft trials of 1692.

Dramatic river bend surrounds a natural red-rocked pedestal.

La Monte Young and Marian Zazeela's "Dream House" will immerse you in an ever changing world of sound and light.

America's most famous museum of medical oddities is home to the remains of Albert Einstein's brain.

A classic Route 66 landmark that was built with scrap lumber and is held together with kitsch and puns.

The neon signs from Las Vegas' past find their final resting place at this unusual graveyard.

Most-visited and most-photographed slot canyon in the American Southwest.

An homage to everyone's favorite prehistoric cartoon family.