"Attack Tower. Attacks nearby enemies by shooting large arrows."
Great Ballista is a defensive building which automatically fires great arrows with little noise, damaging and often taking multiple infected down. Its attacks have a knockback effect (similar to Sniper's attack) on enemies. The attack priority can be set to either the nearest target or the highest threat. However, it cannot fire over mountains or forests (but can shoot over large rocks).
Can be upgraded to the Executor, once researched.