World's strongest whirlpool.

Learn the incredible story of how an unassuming spa town was transformed into one of the world’s largest uranium mining sites.

The last moments of the ill-fated Pompeiians, frozen forever in plaster.

A fortified palace in the shape of a ship on the Thiou river.

Dress up like a miner and take a slide into the disco-lit depths of this once foundational salt mine.

A centuries-old copper mine that once provided two thirds of the world's copper supply.

The world's biggest version of the popular Swedish souvenir.

Stockholm's narrowest alley is barely over two feet wide.

An ancient Viking runestone hidden in plain view in Stockholm's old town.

It is said that each of the white stones in the red facade of this medieval house represents the head of a murdered Swedish noble.

It houses the remains of a 17th-century version of the Titanic.

The mortal remains of an estimated 70,000 people lie in the basement of a monastery in Lima, Peru.

The large collection of pre-Columbian pottery might make you blush.

In the upscale neighborhood of Miraflores in Lima, a pretty little park is home to dozens of cats.

This geometric feat is a testament to the Incas' mesmerizing architectural abilities.

Situated on a sacred Inca site, this 16th-century cathedral took nearly 100 years to build.

Built on the remains of one the Incas’ most important gathering spots, this square keeps the spirit of a fallen empire alive.

The stones of this Incan wall complex fit together so well you couldn't fit a piece of paper between some of them.

This Peruvian canyon is filled with geometric salt pools that have been being harvested since the Incan empire.

Huge stone depressions which may have acted as an Incan agricultural experiment.

The intricate stonework of Machu Picchu serves as a testament to Incan engineers.

Preserved Inca city and site of the last Inca stronghold against the Spanish conquistadors.

The NASA scientists behind Apollo 11 started out developing Nazi weapons at this abandoned German rocket factory.

This 1960's Soviet submarine in Peenemünde Harbor claims to be the largest submarine museum in the world.