In Greek and Roman mythology, the Palladium or Palladion (Greek Παλλάδιον (Palladion), Latin Palladium) was a cult image of great antiquity on which the safety of Troy and later Rome was said to depend, the wooden statue (xoanon) of Pallas Athena that Odysseus and Diomedes stole from the citadel of Troy and which was later taken to the future site of Rome by Aeneas. The Roman story is related in Virgil's Aeneid and other works. Rome possessed an object regarded as the actual Palladium for several centuries; it was in the care of the Vestal Virgins for nearly all this time.
Since around 1600, the word palladium has been used figuratively to mean anything believed to provide protection or safety, and in particular in Christian contexts a sacred relic or icon believed to have a protective role in military contexts for a whole city, people or nation. Such beliefs first become prominent in the Eastern church in the period after the reign of the Byzantine Emperor Justinian I, and later spread to the Western church. Palladia were carried in procession around the walls of besieged cities and sometimes carried into battle.
