Allowing humans and fish alike to migrate from freshwater to saltwater and back again.

This grand old 80-foot sequoia towers above the buildings in the city’s retail center.

An old-timey peepshow allows visitors to gawk at some of the world's most freakishly large footwear.

The tech giant built three enormous glass orbs in Seattle so employees could work inside a rainforest greenhouse.

A wall of chewing gum moonlights as collective art.

Running under an entire mountain, the longest highway tunnel in North America is kept fresh using portal fans and jet fans.

This small city where almost everyone lives in the same building can only be reached via North America's longest tunnel.

Clean, cold drinking water flows from a nondescript pipe in a roadside rock face.

During the summer, surfers in Alaska take advantage of this inlet’s unusual water patterns.

A high school astronomy enthusiast designed this model of our solar system to be traversed on foot.

A huge musical sculpture and other art installations on the National Oceanic and Atmospheric Administration grounds.

Florence’s mother built a stairway down to her daughter’s coffin so she could comfort her during storms.

Healing Springs that once ran red with soldiers' blood.

Once decrepit and slated for demolition, now one of the longest pedestrian bridges in the world.

The secret city built by the Manhattan Project.

Spanning the El Chorro gorge, this pathway used to be one of the most dangerous crossings in the world.

Three bridges and one giant canyon make up this fantastic Spanish settlement.

On this tiny spot of land in the middle of Lake Titicaca the only ones who do the knitting are the men.

The Uros people live on floating reed islands in lake Titicaca.

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

A backdoor to Machu Picchu that only the most foolhardy infiltrator would attempt to breach.

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

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

A painting in the historic Cathedral Basilica depicts Jesus and his disciples dining on a traditional Peruvian menu.