Daredevil repair workers can worm their way out the access hatch, loop ropes over the apex and rappel down the monument.

An Industrial Revolution-era public work that purified water using nothing but sand.

This head-spinningly bizarre Depression-era art cave is wall-to-wall quartz and Jesus.

Hiding behind a grocery store is a spectacular cavern carved as part of an old limestone quarry.

Enormous lake at the bottom of a unique cave system.

Legend says a primate-like cryptid prowls this otherworldy sliver of the Louisiana bayou.

This abandoned Civil War fortress is slowly being swallowed by the waters of Lake Borgne.

The birthplace of the Ford Model T is now a museum full of antique cars.

A Beaux-Arts triumph set to become Ford's innovation campus

This scenic fortress dates back at least 2,400 years to the time of Magna Graecia.

The ruins of this Roman temple dominate the small city in southern Lazio.

A fiery crater has been burning in the Karakum Desert since 1971.

Deep below the dry landscape of Bahia, a cave with intense blue water to float in.

The remote resting place of a notorious Wild West outlaw whose death is shrouded in mystery.

These magnificent city walls rise from the barren sun-baked Spanish plains like something straight out of a fairytale.

Get past the gatekeeper's apartment and enter an elaborate hoax of a restaurant with a Masonic feel.

Standing for over 200 years, the abandoned home of a Revolutionary War hero and later a succession of prison superintendents.

According to legend, this cavern holds the passage that Persephone used to travel to and from the underworld.

Τhis feline monument commemorates fallen soldiers on a field that saw many, many battles.

The world’s tallest outdoor lift stretches along the stone pillars that inspired the floating mountains in the movie “Avatar.”

A striped 12th-century basilica sits in the countryside of Sardinia.

This medieval hilltop village was abandoned at the end of the 19th century, after existing for more than 500 years.

This ancient Visigothic church might hide an ancient treasure.

Hundreds of lucky felines haunt the ruins where Caesar was murdered.