From the center of Flagstaff, take US-89 due north until you arrive at the park entrance on the right. About 40 miles to the center of the park.
I love visiting the ruins of the Ancient Puebloans, also called the Anasazi. One of the easiest places to access is the Wupatki National Monument, about 40 miles north of Flagstaff. Several "communities" are within its borders, and the largest, the Pueblo is next to the visitor's center, with paved trails taking you right up to the ruins. It's a place that fills me with wonder and gets my imagination flowing each time I visit.