Eurialo Castle

Archimedes had as enemies the Carthaginians, and knew of their formidable methods of warfare. One of these was the use of "mines" made of "Greek Fire", a lethal mix of brimstone and palm oil, which when lit didn't extinguish and, put into tunnels dug beneath city walls, caused it to collapse. So Archimedes, to combat the destruction of Syracuse, had complicated tunnels dug all around the city, to divert the path of this "mines".