The Masonic Grand Lodge of Arizona meeting in the cave in the mine of the Copper Queen Consolidated Mining Co. at Bisbee, Arizona, Nov. 12th 1897.
I found this photo on the Library of Congress site. Pretty cool. Some lodges in the western part of my state conduct periodic meetings on high hills or in low vales, and I have even heard of cave lodges. However, I have never actually been to any of these meetings. Looks pretty darned cool!