The Fortress of Antonia

Along the northern side of the temple courtyard stood the massive palace - fortress of Antonia, another of Herod's landmarks. A stairway and an underground passageway connected the Antonia with the Court of the Gentiles, and the 600 soldiers stationed there were always on the alert for disturbances in the temple precincts. The precious ceremonial robes of the high priest were kept in one of its four guard towers and were released only on important religious feast days. Bible History Online.