Was in Baalbek in 1962.
Tour guide told us that the huge rocks were hewn in Egypt and transported by boat. Many of them did not make it to place of destination and can be found on bottom of Mediterranean in a line drawn from Alexandria to Lebanese coast.
Place is not too far from Zahleh (Christian area) known for their excellent Labanese cuisine and arak (Lebanese equivalent of Ouzo).
And you believed him?