Machaerus
    the Black Fortress, was built by Herod the Great in the gorge of
    Callirhoe, one of the wadies 9 miles east of the Dead Sea, as a
    frontier rampart against Arab marauders. John the Baptist was
    probably cast into the prison connected with this castle by
    Herod Antipas, whom he had reproved for his adulterous marriage
    with Herodias. Here Herod "made a supper" on his birthday. He
    was at this time marching against Aretas, king of Perea, to
    whose daughter he had been married. During the revelry of the
    banquet held in the border fortress, to please Salome, who
    danced before him, he sent an executioner, who beheaded John,
    and "brought his head in a charger, and gave it to the damsel"
    (Mark 6:14-29). This castle stood "starkly bold and clear" 3,860
    feet above the Dead Sea, and 2,546 above the Mediterranean. Its
    ruins, now called M'khaur, are still visible on the northern end
    of Jebel Attarus.