CHALCIDICUM, or CHALCEDONIUM, in the ancient architecture, a large magnificent hall belonging to a tribunal or court of justice. Festus says it took its name from the city Chalcis; but he does not explain the reason why it did so. Philander will have it to be the court or tribunal where affairs of money and coinage were regulated; so called from χαλκός, brass, and ἀξία, justice. Others say the money was struck in it, and derive the word from χαλκός, and ἀξία, house. In Vitruvius it is used for the auditorium of a basilica; and in other ancient writers for a hall or apartment where the heathens imagined their gods to eat.