If you're taking a summer vacation to Grand Canyon National Park this year, plan to stop and visit Walnut Canyon National Monument. It's only 8 miles east of Flagstaff and a quick 3 miles off Interstate 40. You won't find an easier and more enjoyable way to see extremely well-preserved cliff dwellings. You can spend a couple of hours or a leisurely half-day. Either way, Walnut Canyon is a beautiful and popular side trip as you head to the Grand Canyon.