Complex sentence: It is on the site of a number of former explosives factories; the largest of these was operated by the Giant Powder Company, which was relocated to this relatively remote spot following accidental explosions at its former sites in San Francisco and Berkeley.
Split into simpler sentences: It is on the site of a number of former explosives factory. The largest of these was operated by the Giant company, which was relocated to this relatively remote spot following accidental explosions at its former sites in San Francisco and Berkeley.