Ballista

 are generic units available in the Classical Era, after researching Siege Tactics technology. These units are only trainable before siege starts.
 * Description
 * Evolved from heavy crossbows like the Greek gastraphetes, the ballista is more accurate than the catapult.

Class and Specialty

 * Can only be constructed during a siege using accumulated siege works. Cannot enter city tile or retaliate when attacked by a close-combat unit.
 * Can only be constructed during a siege using accumulated siege works. Cannot enter city tile or retaliate when attacked by a close-combat unit.