When it was built in 1929, this historic bridge was the only place to cross the Colorado River for 600 miles.

Dramatic river bend surrounds a natural red-rocked pedestal.

Most-visited and most-photographed slot canyon in the American Southwest.

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

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

This spectacular track has run continuously since 1882.

The ancient dwellings of the Puebloans, located in the cliffs of majestic mesas.

The hallowed remains of a 900-year old Ancestral Pueblo great house.

This super steep hike ascends 2,000 feet in less than a mile.

Strange red rock formations that have been attributed to a higher power for hundreds of years.

The remains of the dam that unleashed a 15-foot wall of water on Denver.