This canyon is named for a unique geologic formation where the river vanishes underground near the mouth of the canyon and reappears farther down.

This largest dinosaur tracksite in Wyoming is one of the only in the world from the Middle Jurassic Period.

An unusual geological feature towers over the remains of a dark episode in United States history.

The world's largest mineral hot springs is home to a herd of bison, a free public bath house, beautiful mineral formations, and a terrifying swinging bridge.

Long before guestbooks and hotels, frontier travelers signed their names on this rock face.

Native Americans built this circle of stones, which was used to predict astronomical events.

One of nature's most well-scheduled phenomenons resides in Wyoming's Yellowstone National Park.

A legal loophole makes it possible to get away with murder within this 50-square-mile section of Yellowstone.

One home in the historic strip hides secret compartments and the ghostly songs of long-gone canaries.

This small museum is home to some of the oldest and best-preserved dinosaur specimens found in Montana.

Spectacular views await visitors to this lake.

The formidable fowl can be found standing near an isolated hiking path.

The rocks of a certain area of Butte, Montana give off a musical ring when hit.

This amazingly preserved Gold Rush town is a historian's dream.

This park harkens back to frontier life in Wisconsin.

The site of an ancient Mississippian settlement that appears to have flourished during the 10th to 13th centuries.

The tunnel that runs beneath this former inn was once a hiding place for enslaved people seeking freedom.

One of the cave cities of Crimea, built by the Goths in the sixth century.

The ancient ruins of an extinguished city amidst the bustle of a modern one.

A gorgeous and extensive collaboration between biologists and artists, displaying skeletons and other animal remnants in lifelike poses.

The geographical center of Chile is a port so depressing that it has driven men to suicide.

Legend says if this neo-Gothic basilica is ever officially completed, the world will come to an end.

It took 160 years to complete the most ornate church in Ecuador.

An elaborate shrine dedicated to the four corners of the world unfortunately misses its mark.