The working end of the blast furnace, where molten metal would flow like lava out of the furnace… a process called ‘tapping’.
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.
Taken several years before the tornado story when the weather, and the condition of the buildings, were nice.
The blast pit carried the smoke and flame from the rocket motor away from the other base buildings.
There are 700 of these storage bunkers. Their design was to funnel explosions upward, rather than toward other buildings, to minimize secondary explosions.
The middle missile launcher, as seen from the roof of its neighbor.