Powderhouses were used by mines to store their explosives -- originally black powder, later dynamite and similar mixtures. To protect the people and buildings at the mines, powderhouses were built with very thick walls, far away from the mines. The powderhouse at Central is especially ornate, with a doorway lined with bricks -- a huge rarity for the time when it was built. Although the mine is long gone, much of the powderhouse still remains -- as it was designed to do.
Does anyone else think that the lines of this door are reminiscent of an explosion? Perhaps it's just the wide angle.