The prophets were buried there five centuries before Christ, to await the coming of the Messiah (which means Christ), as they themselves foretold.
"Rejoice greatly, O daughter of Sion, shout for joy, O daughter of Jerusalem: BEHOLD THY KING will come to thee, the just and saviour: he is poor, and riding upon an ass, and upon a colt the foal of an ass." Zechariah 9:9