This 12'x12' wood frame D-6 cupola ground cabin with 1/4 size second story cupola was built by the U.S. Forest Service in 1918. One of the hardest to reach lookouts in the U.S., materials were packed up the mountain by mules to 4 miles below the summit, then hauled by four men to the summit using a deadman/rope technique. The structure was in service from 1921 to 1924 as a fire lookout. In 1932, miners began extracting pure sulfur from the volcano's summit vent, and lived in the cabin. Two lean-to additions were tacked onto the original cabin for their use during the next decade. The entire building has been entombed in the summit glacier since mid-20th century and only becomes visible for a few weeks in very dry summers.