 Some time before the close of the fifteenth century, the Parthenon became a mosque.The precise circumstances under which the Turks appropriated it for use as a mosque are unclear; one account states that Mehmed II ordered its conversion as punishment for an Athenian plot against Ottoman rule.The apse became a mihrab, the tower previously constructed during the Roman Catholic occupation of the Parthenon was extended upwards to become a minaret, a minbar was installed, the Christian altar and iconostasis were removed, and the walls were whitewashed to cover icons of Christian saints and other Christian imagery.