Blast Path The lower door is where the rocket exhaust would flow into the blast pit during initial launch. The upper doors would vent the rocket so the erector and other equipment in the building would not be (as) damaged. Related Similar Images ...based on the tags: clouds, ditches, doors, launchpads... The Harrison flour mill, completed in 1897 and expanded in 1901 and 1902. The tunnel that I am standing on probably transported grain from the elevator to the mill. Medium Format. SFAAP’s iconic smokestacks. You’d notice if you drove past this on the highway. From the bottom of the skyway I looked back, my eyes tracing the vines from the marsh up the smokestacks to the perfect Midwestern sky. The Barker turning around before it backed into Tac Harbor to unload coal for Minnesota Power. Taken just after the sun set over Duluth. Don’t you love that green glow? A warped mirror in the rock crusher at the rear of the complex. This skyway, built to help seal off two parts of the complex during an out of control fire, was probably too rotten to burn by the time I saw it. The rear of the complex shows the more than 100 year old workhouse–still working! I do not know if the tanks are original to the 1901 elevator, but I suspect so. These tubes would bring cement to the top of the plant for storage in the silos.