Sunset Crater National Monument

Located just a few miles north of Flagstaff, Arizona on Highway 89, Sunset Crater is one of the most
accessible National Monuments in Arizona. Quoting from Wikipedia,

The eruptions forming the 340-meter-high cone (1,120 ft) were initially considered from tree-ring dating to have begun between the growing seasons of 1064–1065 AD; however, more recent paleomagnetic evidence places the onset of the eruption sometime between about 1080 and 1150 AD. The largest vent of the eruption, Sunset Crater itself, was the source of the Bonito and Kana-a lava flows that extended about 2.5 kilometers (1.6 mi) NW and 9.6 kilometers (6 mi) NE, respectively. Additional vents along a 10-kilometer-long fissure (6.2 mi) extending SE produced small spatter ramparts and a 6.4-kilometer-long lava flow (4 mi) to the east. The Sunset Crater eruption produced a blanket of ash and lapilli covering an area of more than 2,100 square kilometers (810 sq mi) and forced the abandonment of settlements of the indigenous Sinagua Indians.

The elevation of the Monument is 8,042 feet and even summer weather can be cool to chilly. Recent forest fires around Flagstaff have come close to the edge of the National Monument but no fires have recently burned inside the boundaries.  There are some interesting short hiking trails and a few viewpoints but the whole National Monument can be seen in a matter of hours. There is a large campground in the National Forest outside the Monument with an additional large group campsite, but other than camping and Ranger presentations, there are not many other things to see and do. Even though it is small, it is well worth the visit.