The Saylor kilns in Coplay are the world's only remaining continuous-firing vertical cement kilns, also known as Schoefer kilns. Constructed as Coplay Cement's Mill B in 1892, they were the last major innovation in vertical kiln technology. They operated for only about a decade before the cement industry, facing soaring demand for portland cement, adopted the more efficient and productive horizontal rotary kiln. The Schoefer kilns were shut down about 1904, and Mill B was converted to a bagging house, a continued use of the surrounding building that probably helped preserve them. While successful cement plants like Coplay often demolished old structures as technology improved, these kilns survived; though scheduled for demolition in 1951, they were instead shortened by 40 feet for safety reasons. In 1976, Lehigh County created Saylor Park in part to help preserve these symbols of Coplay's cement heritage, although much restoration is still needed.
