Some 60 million years ago, a prehistoric river carved a deep bowl in the earth about 10 miles east of present-day Flagstaff. Walnut Canyon, a chasm 20 miles long, 400 feet deep, and a quarter-mile wide, served as home to an ancient people for over a century. Here they lived in limestone cliffs' natural alcoves or in pueblos and pit houses built from rock. The last residents, known as the Sinagua (meaning "without water," a nod to the region's aridity), departed 800 years ago. President Woodrow Wilson declared the gorge a national monument in 1915 to preserve the timeworn abodes.
The best time to visit is March, when local archaeologists lead hikes and give talks. A walk along the Island Trail descends a steep 185 feet, passing by 25 cliff dwellings—some with masonry walls intact—where the Sinagua cooked, slept, and watched for intruders.
For an easier hike, follow the three quarter-mile Rim Trail through piñon and juniper forest. Diverse flora draws an abundance of wildlife, such as golden mantled ground squirrels and ornate tree lizards. Birdsong, from the staccato peeps of Townsend's solitaires to the descending trills of canyon wrens, fills the quiet of the ravine.
Remnants of a pit house and an earth-hued pueblo are visible from the path, and the nearby visitor center displays Sinagua artifacts, including sandals, textiles, serving bowls, pitchers, and other domestic items.