n 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
worshippers of Jupiter. Among the statues wrought of this marble may
be mentioned the famous group of the Laocoon found in the Baths of
Titus; the beautiful Venus de Medici, discovered in the Villa of
Hadrian, near Tivoli, and now in the Uffizi Gallery in Florence; and
the well-known "Farnese Bull," sculptured out of a single block of
huge dimensions, unearthed out of the ruins of the Baths of Caracalla,
and now in the Museum of Naples. Massimo d'Azeglio, in his
_Recollections_, gives an interesting instance of the value set upon
this marble by modern Roman sculptors. Pac