Photograph of construction of Boulder Dam, showing a work site on a canyon wall, ca.1930. The torsos of several men in suits and hats can be seen on the bottom in the foreground with a small, wooden shed to the left of them and the canyon wall behind them. A pulley hangs down on the left with a wooden porch standing in the rock wall on the far left. A wooden staircase connects the porch to a flimsy, wooden structure at the top of the wall. A wooden tower stands above the rock at center with wires extending through its frame and to the right. Metal towers stand in the opposing canyon wall in the background on the far right.