An icon to American artillerymen, far in the distance on the highest point is Block House, Signal Mountain. Originally, used as a signalling post and weather station from the 1870s, has been on Fort Sill's West Range since the 1940s. Any US artilleryman will know Block House, Signal Mountain as an aiming point for gunnery or observation exercises...
I can remember doing "graded shoots" as a forward observer in the artillery lieutenant basic course in 1982... Your gunnery instructor would call out, "To identify, three fingers left of Block House, Signal Mountain, and at a lesser range, your target..." I remember it like it was yesterday, the stop watch would click and you'd have seconds to identify, locate, and initiate the call for fire.
This photo is from sometime in the 40s/50s.