Parian marble, we see the first example in Rome of the use of ornaments in marble upon the outside of a building; an example that was afterwards extensively followed, for all the tombs of a later age on the Appian Way had their exteriors sheathed with a veneer of marble. The beautiful sarcophagus which contained the remains of the noble lady for whom this gigantic pile was erected, and which is now in the Farnese Palace, was also formed of this material. Most beautiful examples of Parian marble may be seen in the three elegant columns of the Temple of Castor and Pollux in the Roman Forum, belonging to the best period of Graeco-Roman architecture; and in the nineteen fluted Corinthian pillars which form the little circular temple of Hercules on the banks of the Tiber, long supposed to be the Temple of Vesta. By far the largest mass of this marble in Rome is the colossal fragment in front of the Colosseum that belonged to the Temple of Venus and Rome; and it helps to give one an idea of the extraordinary grandeur and magnificence of this building in its prime, whose fluted columns, six feet in diameter, and the sheathing of whose outside walls of great thickness, were all made of Parian marble. More extensively employed in Greek and Roman statuary and architecture was the _Marmor Pentelicum_, or Marmo Greco fino of the modern Italians. The quarries which yielded inexhaustible materials for the public buildings and statues of Greece, and for the great monuments of Rome, were situated on the slopes of Mount Pentelicus, near Athens; and after having been closed for ages, have recently been reopened for the restoration of some of the buildings in the Greek capital. The marble is dazzlingly white and fine-grained, but it sometimes contains little pieces of quartz or flint, which give some trouble to the workmen. The Parthenon, crowning like a perfect capital of human art the summit of Nature's rough workmanship in the Acropolis, was built of this marble; and the immortal sculpture of Pheidias on the metopes, the frieze of the cella, and the tympana of the pediments of the temple, known as the Elgin Marbles, were carved out of a material worthy of their incomparable beauty. Innumerable specimens at one time existed in Rome. The arch of Septimius Severus and the Arch of Titus are built of it, although the rusty and weather-beaten hue of these venerable monuments hides the nature of the material. Domitian, who restored the celebrated Temple of Jupiter on the Capitol, procured columns of Pentelic marble for the purpose from Athens; two of these are now in the nave of the church of Ara Coeli, built upon the site of the temple; and portions of the others, and of the marble decorations, were presented by the magistrates to the Franciscan friars of the neighbouring convent, and by them were wrought in 1348 into the conspicuous staircase leading to the facade of the church, which pious Catholics used to mount on their knees in the manner of the ancient