The first railway tunnel to cross the Continental Divide and, at 11,523 feet, was once the highest railroad tunnel in the world.

An impressive collection of over 50,000 minerals including moon rock from the Apollo 17 mission.

The clock that sets them all.

These decaying bridges 1,000 feet high are a reminder of the skill it took to cross the Colorado Rockies by rail.

At the tallest peak in Colorado, an electrifying mix of thin air, lightning, and rivalry.

A little-known hot spring haven right below the highway.

Colorado's only true geyser is hidden within the San Juan National Forest.

The highest paved road in North America winds its way up Mount Blue Sky in Colorado to an altitude of 14,130 feet above sea level.

This spectacular track has run continuously since 1882.

Minnesota's highest point is a scenic vista marked by a plaque and armies of mosquitoes.

A piece of solitude and tranquility in the heart of East Saint Paul.

This "railway" for boats continues a waterway over a road.

Cliffs that hold fossils, including the earliest known reptile, dating back more than 300 million years.

One day a year it is legal to jump off of this astoundingly tall bridge that spans an Appalachian gorge.

The water swaps direction twice a day, whipping into a frenzy of whirlpools and rapids.

Foragers once flocked to this big beautiful bayou to hunt for pearls.

The only international border marker within the United States.

The only geyser in the state of Pennsylvania is caused by pressure from an abandoned coal mine outside of the ghost town Centralia.

This towering volcanic plug stands out among the dramatic formations that dot this otherworldly desert valley.

This highest peak in New Mexico is named after an explorer who had a habit of lending his monicker to peaks.

Wedding chapel's mysterious spiral staircase said to be miraculously constructed.

A giant granite cross remembers missionary Father Frederic Baraga, and his safe passage across an angry Lake Superior.

This vintage "streetcar boat" lay at the bottom of Lake Minnetonka until the 1980s.

Journey through the largest remaining peat bogs in the contiguous United States to see the wilderness as it once was.