Harquahala Peak Observatory was built in 1920 by the Smithsonian Astrophysical Observatory to measure and record solar activity. Although deserted now, from 1920-1925 a hardy group of scientists lived and worked atop the highest mountain in southwestern Arizona (5,681-foot elevation). How these individuals lived, worked, and relaxed up on this peak, struggling with its seclusion and weather, represents an enlivened story of dedicated scientific pursuit and American inventiveness. Visit the Observatory | History of the Observatory Visit the Observatory The observatory is at the top of Harquahala Peak. You can get to the peak via the rugged, 10.5-mile Harquahala Mountain Back Country Byway . A steep hiking trail also leads 5.6 miles to the summit via Harquahala Pack Trail Basecamp Trailhead . Know Before You Go Watch for rattlesnakes and other venomous creatures in the desert. Please do not harass reptiles. Many people are bitten while playing with, collecting, or attempting to kill them. Remnants of prospecting and mining lie near the Observatory and elsewhere in the Harquahala Mountains. Be aware of the danger these remains pose and avoid them when exploring the area. Thunderstorms on Harquahala Peak are often violent and dangerous. Should stormy weather arise during your visit, leave the mountaintop as quickly as possible.