One of the few standing Roman lighthouses and a labyrinth of tunnels are a couple of the secrets at this historic castle.

In this cobwebbed old operating theater, you can practically hear the screams of the unanesthetized patients.

One part local history, 99 parts gruesome haunted house.

Thanks to both terrific preservation and historic vandalism this ancient site is known as the "Heart of Neolithic Orkney."

Possibly the oldest of Britain's ancient henges is also one of its most stark.

The true age of this ancient stone circle is unknown, but its stunning vista isn't in question.

The picturesque birthplace of Icelandic democracy is drenched in the blood of its brutal past.

If a glacial river suddenly diving into a sheer chasm via a dramatic, multi-stage waterfall isn't peak Iceland, it's certainly close.

This elegant arc of a waterfall marks a religious turning point.

Terrifically morbid cemetary and site of famous Paracelsus' grave.

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

Dyed by iron oxide over centuries, these sandstone rocks rise thousands of feet into the sky.

Copenhagen's celebrated theme park and gardens.

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

Swedish skyscraper with a 90° twist.

Salute the leader of the proletariat.

The final resting place of 121 victims of the RMS Titanic, 42 of which may never be identified.

One man's exploration of the human form, including the bizarre and delightful "Man Attacked by Babies."

Commemorating the spot where the famous scientist fed his pigeons.

The former hotel where Tesla invented the radio.

This abandoned coliseum was intended to be a grand Nazi rallying ground before it was halted at the end of the war.

Macabre astrological automaton clock dating to the late 1400s.

Home to three historic ships from the age of Vikings.

Museum celebrating the ocean, with the largest wunderkammer dedicated to sea exploration.