Alburtis, PA, United States
Lock Ridge Iron Furnace. Representative of the many iron furnaces in the Lehigh Valley, Lock Ridge was constructed here in 1868, operated until 1921, and was the last furnace in the US to solely use anthracite coal as fuel. By the late 19th century the Lehigh Valley was the state's largest producer
of pig iron. Among the only remnants of Pennsylvania's anthracite iron industry, the partially restored complex is listed on the National Register of Historic Places.
Listen to the audio guide for Blue plaque № 29155 Free on WIP — starts by itself when you arrive, even with the screen off