The chief supply of pure white marble in Rome was derived from the quarries in the mountains at Luna, an old Etruscan town near the Bay of Spezia, which fell to decay under the later Roman emperors.  This ancient Marmor Lunense is called by the Italians Marmo di Carrara, because it is identical with the famous modern Carrara marble, and belongs to the same range of strata; the ruins of the ancient Luna being only a few miles from the flourishing town of Carrara, the metropolis of the marble trade.  From Parian and Pentelic marble, Lunar marble, as already mentioned, can be easily distinguished by the less brilliant sparkle of its crystal facets, as shown by a fresh surface, and also by its more soapy-white colour.  It is simply an ordinary Jurassic limestone altered by subsequent metamorphic action.  The mountains which contain the quarries are highly picturesque, rising with serried outline to a height of upwards of five thousand feet, their flanks scarred by deep gorges and torrent-beds, and their lower slopes clothed with olive groves, vineyards, and forest trees.  Lunar marble was first brought to Rome in the time of Julius Caesar; and Mamurra, so bitterly reviled by Catullus, the commander of the artificers in Caesar’s army in Gaul, lined with great slabs of this marble the outside and inside of his house on the Coelian Hill—­the first recorded instance of veneering or incrusting walls with marble.  The discovery of this method of cutting marble into thin slices, and decorating structures of ordinary materials with them, was stigmatised by Pliny as an unreasonable mode of extending luxury.  The use of Lunar marble, on account of its easy accessibility, speedily extended to every kind of building, public and private.  So vast were the quantities sent to Rome, that Ovid expressed his fear lest the mountains themselves should disappear through the digging out of this marble; and Pliny anticipated that dreadful consequences would be produced by the removal in this way of the great barriers erected by Nature.

Many fine specimens still survive the ravages of ages, among which may be mentioned the eleven massive Corinthian columns, upwards of forty-two feet high, and four and a half feet in diameter, which form the peristyle of the Temple of Neptune in the Piazza di Pietra, well known as the old Custom-house.  These pillars suffered severely from the action of fire, and are much worn and defaced, but there is a grandeur about them still which deeply impresses the spectator; and the blocks of marble which form the inner part of the architrave and entablature, as seen from the inner side of the court, are so stupendous that the ruins “overhang like a beetling rock of marble on a mountain peak.”  Grander still is the majestic column of Lunar marble dedicated to Marcus Aurelius, in the Piazza Colonna, which rears aloft its shaft one hundred and twenty-two feet in the air, wreathed around with spiral bands of historic reliefs, illustrating the Roman conquests