How big is a ballista?

A ballista is a large ancient missile weapon that resembles a giant crossbow, typically measuring around 10 to 20 feet in length. Its size can vary based on its design and intended use, with some larger versions being even more substantial. Ballistae were used in ancient warfare to launch projectiles such as bolts or stones over long distances. Their construction often included a wooden frame, torsion springs, and sometimes a wheeled base for mobility.