The only road through the heart of Glacier National Park.

The world's tallest turtle riding the world's largest snowmobile.

The remnants of an early American attempt at missile defense.

The largest Walleye statue in the world calls this Minnesota town home.

A replica viking ship from the Chicago World's Fair is still in dry dock in an Illinois park.

This massive airship factory is so large that it has its own indoor weather.

Fresh wooden posts have been added to ancient holes to recreate a primitive henge clock.

Once one of the world's great cities, Cahokia was a place of religious worship, trade and mass human sacrifice before being mysteriously abandoned.

A monument celebrating the idea of reaching inaccessible places.

The marker offers a rare chance to be in four U.S. states at once, though there's some controversy over its geographic accuracy.

Red sandstone structures dominate this landscape, which has been inhabited for some 5,000 years.

A once popular resort—said to be the vacation spot of gangster Al Capone—now remains abandoned in the woods of Arizona.

At an isolated roadside rest area stands a monument marking where famous Western star Tom Mix died in 1940.

The remote resting place of a notorious Wild West outlaw whose death is shrouded in mystery.

A massive volcanic plug is now a protected area that hosts a number of bird species.

A dwindling menagerie of anthropomorphic oil derrick animals still dot the barren California landscape.

Dyed by iron oxide over centuries, these sandstone rocks rise thousands of feet into the sky.

Ninety feet off the valley floor is an ancient dwelling put under protection of the U.S. government by Teddy Roosevelt.

Inside this striking glass building, visitors can see thousands of dinosaur fossils in the positions that nature deposited them more than 150 million years ago.

The first declared National Monument in the United States.

This museum is a full-size replica of an original church constructed during the 13th-century.

A six-ton, 12-foot-tall concrete prairie dog is touted as the largest in the world.

Bootleggers ran booze beneath this building before (and after) Route 66 appeared beside it.

At this Minnesota state park you can easily wade across the source of the mighty Mississippi.