As the church’s fortunes grew under King Coal, the windows were added. Its most interesting feature, however, might be in the basement, where one wall isn’t really a wall at all. It’s the side of Flagstaff Mountain. In spring, when the ice thaws on the mountain, water seeps through the rocks in the church. Designed by architect Richard Upjohn in 1869, the church is so integrated into its environment that supporters fear the rock could shift and slide during the county’s project, damaging much more than glass.