The ruins of a once-grand castle that played host to a tournament with 100,000 attendees.

Dedicated to a veritable Houdini among P.O.W.s who escaped imprisonment on five separate occasions.

Decades before the Salem Witch Trials, two Connecticut women were executed for alleged witchcraft.

This stone bridge is all that remains of a submerged New Jersey town.

The remains of "the Pearl of Scotland" can be found inside this church.

It's been nearly a century since this volcano, the tallest mountain in Equatorial Guinea, erupted.

This iconic Lancaster everyman has been reading the same story since 1980.

Believed to be the smallest castle in Europe.

Long-abandoned art nouveau baths beneath Milan's Piazza Oberdan.

These unusual stone structures are actually fish traps crafted by an ancient civilization.

An enormous sinkhole that local lore attributes to the anger of the Virgin Mary.

Remains of the lost church hide beneath this Spanish Parliament building.

A subterranean relic of the Spanish Civil War hides below this picturesque park.

A collection of weird and wonderful art fills a former houseplant nursery.

A 13,000-year-old mastodon skeleton was found during the construction of a 19th-century New York mill.

The abandoned ruins of a beautiful medieval castle just outside Barcelona.

The oldest cemetery of modern-day Athens blends the modern and ancient worlds.

A simple tribute to the migrant workers who landed here before walking hundreds of miles to Victoria's gold mines.

Crossing this suspension bridge feels like walking through the sky, a fitting tribute to the head of the Apollo program.

Albert Einstein's head sticks out of a snail shell stacked on a rocket in this truly bizarre monument to the scientist.

A bright turquoise river cascades beautifully down stepped terraces in southern China.

A crescent of 12 simple statues poised on a small windswept island off the coast of Newfoundland.

This meticulously extracted nervous system allegedly came from a 19th-century custodian who donated her body to science.

Tucked away along a riverbend in an area known for its uranium mines is one of the world's tallest locks.