The first ballista was built in 400 BC for Dionysius of Syracuse by the Greeks. With the invention of torsion spring bundle technology by the Ancient Greeks, the first ballista was able to be built. This allowed lighter projectiles to be shot with higher velocities over longer distances. It was a highly accurate siege engine, and was similar to a giant crossbow and worked by using tension. The two arms of a ballista were made out of wood and the ropes were made out of twisted skeins. Although the ballista was highly accurate, its range was less than that of a trebuchet. The projectiles launched by the ballista were significantly lighter than the heavy trebuchet stones and could not gain the momentum of the heavier missiles.
These materials were used by the Greeks to build the first type of ballista: Torsion springs, Twisted skeins, Iron plates, Iron nails, Taut Springs, Bronze caps, and Wooden Planks.
Mining in the Iron Age allowed metals like iron, silver and bronze to be used in the battlefield. Although the main material used was still wood, metals allowed ballistae to be more stable after they were used. The silver mines in the mountain of Lavrion, Attica in Greece started in 1500 BC. These mines reached its zenith in 600-400BC. Until the beginning of 500BC, opencast mining was the main form of extracting metals from the earth but underground mining became more and more popular. This resulted in the production of about 2,000 shafts with a total length of 140km. In 500BC, 10,000 - 30,000 miners worked in the silver mines of Lavrion.