Half of a waterfall goes into the river while the other half seems to disappear.

This large midwestern cavern features impressive rock formations and an underground waterfall.

This building is a recreation of the gatehouse that separated Los Alamos from the outside world during the era of the Manhattan Project.

A short tunnel built straight through a magmatic dike.

You can find America's highest suspension footbridge at Grandfather Mountain in North Carolina.

A lava tube cooled to form this long tunnel that stays chilly even at the height of summer.

Dedicated to extinct passenger pigeons.

A 20-foot-tall quarter commemorates George Washington’s ties to Bedford County.

How did a 154-foot-long piece of spacecraft wind up abandoned along the side of a Florida road?

Overshadowed by the theme park opposite it, this small museum explores a major moment in American history.

This small museum inside a larger sports complex honors the first Native American to win an Olympic gold medal for the U.S., and his life of achievement and struggle.

A short interpretive trail about one of the first human cultures in North America.

A series of silhouettes that recall the great cattle drives of the 19th-century.

This 19th-century house museum features a horse-drawn hearse and other antique oddities.

This small canyon park was once the main street of Silver City—until a flood washed it away.

Tacoma's historic Beaux-Arts train station is now a federal courthouse featuring large-scale glass sculptures by artist Dale Chihuly.

The gambling entrepreneur who built a city was also an avid collector of classic cars.

Nature has shaped this drainage tunnel into the digestive tract of a mighty beast.

This small museum is home to cannons cast by Paul Revere and the last remaining uniform of Egyptian President Anwar Sadat.

A sacred collection of indigenous rock art.

A massive museum preserving the United States culture and the home of Abraham Lincoln's sleigh.

This redwood is a historic landmark, a town’s namesake, and the dancing sideline symbol of Stanford University.

This unique landscape is the only place in the world to dig for hourglass-selenite crystals.

The home of possibly the least-loved U.S. president stands as a sort of unpopular Monticello.