A miniature train-ride through Slovenia's largest cave system.

Where the lovelorn find a home for their sentimental keepsakes.

A chain of 16 wondrous lakes formed as a result of the gradual dissolution of soluble layers of bedrock.

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

The world’s first penitentiary, meant to be humane, drove men insane.

Instruments, apparatus, and rare books all relating to chemistry and its related sciences.

Solar powered Spectacle Island features all-green facilities.

Impossibly life-like natural history models created out of glass by a father and son.

Three prestigious academic collections come together to create a world-class natural history museum.

Two thousand artifacts from around the world collected by one woman who loved to travel.

Bouncing, delightful, mechanical art at the MIT Museum.

An enormous, inside-out glass globe built in 1935.

This impressive Boston holy house is the American mecca for Christian scientists.

19th-century operating theatre in which the use of ether was first demonstrated - plus, a skeleton and a mummy!

Macabre headstones carved with winged skulls, dancing skeletons, and pithy reminders of impending death.

An interesting decoration on this historic site, this weathervane comes with as many legends as it does questions.

A former waterfront market is now in the center of town due to some interesting Boston engineering.

Infamous marsh filled with toxic waste, World War II-era London rubble, and dead mobsters galore.

Mysterious 500-year-old tapestries depict a unicorn hunt.

A unique sculpture park that specializes in the huge and bizarre.

A unusual sanctuary for abused and exotic animals in South Jersey.

Vacant Beaux-Arts buildings that serve as reminders of a beach town’s glory days.