From the early 1900s through the 1970s, Pittsburgh was one of America’s leading steel manufacturing towns, producing over 20 million tons of steel annually by the early 20th century. The hills of western Pennsylvania were rich with iron ore—the key raw ingredient for steel—but setting up shop within these hills resulted in Pittsburgh building some of the steepest and most lung-busting streets in America.For the thousands of steel workers living up on the hills that surround the city center, “commuting” to the factories downtown was a grueling ordeal. In addition to constructing a series of mechanical funiculars that connected the hilltops to downtown, the city built long stairways to help Pittsburghers get to work and back up again without injuring their calf muscles. While you couldn’t call climbing these stairways “easy,” the flat steps were a slightly less arduous alternative to the relentlessly angular grade of Pittsburgh’s steep streets.