Charleston is graced by a considerable amount of brownstone in facades, sills and steps, as well as sidewalk “mounting blocks”. This sedimentary rock is truly a form of sandstone, made naturally in America’s Northeast by millions of years of the earth’s crust compressing sand particles into formations that percolate with iron oxides that give it distinctive color. Brownstone became hugely popular as an exterior veneer just prior to the Civil War, and most of Charleston’s brownstones are 1850‘s vintage, such as the 1853 bank building at 1 Broad Street. Brownstone cladding is typically a four-inch veneer joined by masonry to an inner wall of framing or brick, and is a stone that is easily cut because of its relatively soft nature. However, masons impatient to ship brownstone often cut it before it completely dried out, and to show off its color, it was often applied vertically, what is called “face-bedding”, both of which contribute to flaking (spalling) as water seeps through cracks and promotes breakage. Quite a few local brownstone window sills show evidence of spalling, probably due to the heavy dripping of water on stone that was hastily installed. The largest brownstone in the city is the Cathedral of St. John the Baptist, begun in 1890 as a replacement for its predecessor, the 1853 Cathedral of St. John and St. Finbar, which was the largest stone building in the South. Brownstone was so expensive that the newer cathedral was not completely finished, lacking a steeple until 2010, when the belfry was completed with composite brownstone.