One of the Seven Wonders of the Modern World holds the world's tallest metal staircase.

The oldest badlands in North America, Makoshika State Park takes it name from the Lakota words for broken land.

See massive fossils that are over 200 million years old in northeastern Arizona.

This historic national park is covered in the stunning ruins of red rock pueblos.

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

An architect's childhood fantasy treehouse made real.

A beautiful geyser under environmental threat.

The largest hot spring in the United States is, as the name suggests, a stunning show of natural color.

An apocalyptic seismic event creates a deadly chain reaction that ends with a 6-mile long lake developing within weeks.

The only road through the heart of Glacier National Park.

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

This lovely, if imposing, piece of Canadian gothic is possibly the most photographed hotel in the world.

Montreal's giant farmer's market is a foodie's best friend, especially in the winter months.

Designed by Buckminster Fuller, this relic of the 67 Expo survived fire and ice.

A grand Gothic Revival basilica with stained glass depictions of Montreal's religious history has only one soul resting in its crypt.

"Dark Sky Park" is heaven on Earth for astronomers, one of the rare U.S. locations with no artificial light pollution.

When the Austin Dam failed it destroyed much of Austin...and then it failed again.

Contrary to what one might expect, ice forms inside this small cavern during the summer and melts during the winter.

Frank Lloyd Wright's most iconic home dangles over a Pennsylvania waterfall.

A toxic ghost town sitting atop a massive coal fire.

Profile of a sleeping person 4km long in 250m high cliffs.

The last holdout of a pre-Civil War rebel who took the matter of slavery into his own hands.

A historic coal mine that doubles as a museum and tourist attraction.

Once connected to the outside world by a single train track, this ghost town is looked after by the National Park Service.