This 30-foot pile of rocks may be the grave of a mythological Irish queen.

Achill's most recently abandoned village dates back to to the Age of Enlightenment.

A retired military stronghold on the rolling green coast of Donegal.

Two stunning 17th-century libraries and a cabinet of curiosities.

Monument to a suicide protesting the Soviet invasion.

Despite attempts by local police to discourage it, Beatles-inspired graffiti has been a means for artists to air grievances for decades.

Synagogue built from the stones of Solomon's temple contains the golem of Prague.

A 400-year-old mummified arm dangles from the ceiling of St. James the Greater, serving as a warning to thieves.

A church of bones, decorated with 40,000 human skeletons.

These medieval skyscrapers dominate the skyline of this small Tuscan town.

The mummified relic of St. Catherine sits forever on a golden throne.

A diverse collection of wax, bone, papier-maché and mummified relics.

Go inside to really appreciate this 500-year-old technological masterpiece.

A mysterious chasm in the heart of the ancient Roman Forum, the Lacus Curtius was once believed to be a gateway to hell.

Macabre astrological automaton clock dating to the late 1400s.

The world's largest kaleidoscope, designed by a 1960s psychedelic artist.

For over 80 years, Mayan ruins stood proudly in a most unlikely location.

"A hideous albatross in the Hudson River Valley."

The Hudson River School comes alive at this palatial estate.

Collapsing castle on the Hudson river was once the storage site of military surplus business.