Josephus Describes the Building of the Ramp
“He [Flavius Silva, the local Roman commander] had discovered only one spot capable of supporting earthwork. For in rear of the tower which barred the road leading from the west to the palace and the ridge, was a projection of rock, of considerable breadth and jutting far out, but still 300 cubits [450 feet] below the elevation of Masada; it was called Leuce [white]. Silva, having accordingly ascended and occupied this eminence, ordered his troops to throw up an embankment. Working with a will and a multitude of hands, they raised a solid bank to a height of 200 cubits [300 feet]. This, however, being still considered insufficient stabling and extent as an emplacement for the [war] engine, on top of it was constructed a platform of great stones fitted closely together, 50 cubit [75 feet] broad and as many high. The engines in general were similarly constructed to those first devised by Vespasian and afterwards by Titus for their siege operations. In addition a sixty-cubit [90 feet] tower was constructed entirely cased in iron, from which the Romans by volley of missiles from numerous quick-firers and ballistae quickly beat off the defenders on the ramparts and prevented them from showing themselves. Simultaneously, Silva, having further provided himself with a great battering ram, ordered it to be directed without intermission against the wall, and having, though with difficulty, succeeded in effecting a breach, brought it down in ruins.”
From Henry St. John Thackeray, Josephus with an English translation, v. 3, The Jewish War, Books IV–VII (London: W. Heinemann, 1928), 7.8.5, p. 591.