Two Vents at Four The two exhaust vents coming out from the boilers en route to the stacks. Plywood marks where where catwalks were removed to extract equipment. Similar Images ...based on the tags: cables, catwalks, grates, orange, rusty, vents... Mounted in an office. One of the many fireproof bridges connecting the factory sections, one way to prevent fires from spreading throughout the plant. One of a few dozen steel bed frames left in the rubble of the collapsing building. Debating immigrants. The many levels of catwalks make for a place where you can look from the ground floor to the roof, about 4 stories up. The side of King that faces the lake is stained yellow-green. Latscher. Brick Graffiti Series. A long exposure of the city glow illuminating the roof, highlighting the victorian and gothic influences on the brew house. Dust explosions were a real risk for grain mills. These funnels helped to filter the air in the mill.