East Cell Block is a six-tier-high structure built entirely of steel and listed in the Guinness Book of World Records as the world's largest free-standing steel cell block because it is not connected to any outside wall. Each tier has two ranges of fifty cells, and the seven-by-nine-foot cells held two men each for a total capacity of 1,200 men. At the end of each range, a guard's room contained the door-closing mechanism. Each cell had a metal ticket on a rack, and pulling a lever released all the tickets and cell doors at once, while turning a crank drove chains along the range to open or close the doors. Though antique now, the system was state-of-the-art in the 1950's. Some inmates played a game of chicken with the closing doors, and one man was killed when his head was caught and crushed. At the center of each tier, a door opened to the alley, which contained the cells' utilities. When prisoners flooded their cells, guards could enter the alley to shut off the water, and they also used the alley to listen through cell vents for conversations that might reveal trouble. Once each shift, a guard had to walk the length of the alleys on narrow catwalks. The vent at the back of the cell was said to function like a local telephone exchange, allowing someone standing on the toilet and cupping his hands over the vent to talk with someone several cells away, though it was a party line with much interference.