America's most famous piece of self-built architecture.

This Boston medical museum features the skull of the famous medical case of Phineas Gage.

This massive library holds what was once the largest book collection in the world.

Under the right circumstances, this waterfall in Yosemite briefly turns a luminescent fiery orange.

This 1,300 year old monastery built atop a single rock was once only accessible depending on the whims of the tide.

It should come as no surprise that the best view of the Hollywood sign is from Batman's lair.

This secluded aqua waterfall in the Grand Canyon is the perfect swimming hole, and the Havasupai tribe's fiercely protected natural wonder.

A theme park that suffered massive flooding during Katrina was abandoned, and now proves irresistible to trespassing explorers.

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

The world's only museum devoted to the wonders of fluorescence.

A collision of human error and natural geothermal pressure created this rainbow-colored geologic wonder.

It took 82 years and four different plaques to finally get the story right.

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

A paradisical gorge with rapids, waterfalls, and wildlife whose raw beauty is the stuff of CGI movies.

A jungle cave in Peru of unknown depths, otherworldly sounds, and strange nocturnal birds that navigate by echolocation.

If you’ve ever seen a picture of Machu Picchu, then you’ve seen a picture of Huayna Picchu—you just didn’t realize it.

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

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

A fascinating little museum all about the rich history of Peru’s famous plant.

Did Inca children also slide down these smooth rocky slopes above Cusco?

Death rituals and sacrifice inside a Peruvian megalith.

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

Keshwa chaca, among the last handwoven Incan bridges, crosses Apurimac Canyon in Peru.

This antique rail car has been reborn as an urban cafe.