Old Rome: A Handbook to the Ruins of the City and the Campagna

by Robert Burn

Pantheon.

At the same time with his Thermæ, which occupied this district, Agrippa built the famous dome, called by Pliny and Dion, and in the inscription of Severus on the architrave of the building itself, the Pantheon, and still retaining that name, though now consecrated as a Christian Church under the name of S. Maria ad Martyres or della Rotunda. This consecration, together with the colossal thickness of the walls, have secured the building against the waste of time, and the still more destructive attacks of the barons of the Middle Ages, who destroyed most of the other great edifices of imperial Rome by either making them their strongholds or pulling them down for building materials. The pronaos rests upon sixteen granite columns, with marble Corinthian bases and capitals. It was formerly approached by six steps, but two only are now above the level of the surrounding ground. The architrave and frieze are plain, and on the latter stands the inscription, which formerly, as may be seen by the holes for nails, was formed by metallic letters:

M . AGRIPPA . L . F . COS . TERTIUM . FECIT.

Agrippa was consul for the third time in B.C. 27, so that the building is now 1906 years old. Another inscription in smaller characters stands under this upon the two upper ledges of the architrave, commemorating the restoration of the building by Severus and Caracalla. The pediment, as may be seen by the holes of the metal fastenings, formerly contained a bronze relief representing Jupiter hurling thunderbolts upon the giants. The roof of the pronaos was originally arched, but the vaulting has been replaced by strong beams, and on the outside the gilded bronze has been replaced by lead. In the interior of the pronaos, on each side of the entrance are two huge niches which formerly contained the statues of Augustus and Agrippa, but are now empty.

The pronaos is connected with the rotunda by two massive projections of masonry ornamented at the sides with marble pilasters and exquisitely worked reliefs in pentelic marble representing candelabra and sacrificial implements entwined with wreaths. These connecting walls originally rose to an equal height with the walls of the rotunda, but are now hidden by the bell towers, erected by Bernini in the time of Urban VIII. about A.D. 1625.

The doorway is of magnificently carved marble slabs, and the folding doors, moving on massive hinges fixed in two projecting pilasters, are of exquisitely worked bronze.

The rotunda rests on a rectangular base, similar to those which support the cylindrical part of the mausoleum of Hadrian and the tomb of Cecilia Metella. In the parts where the thickness of the wall is not lessened by niches in the interior, it has the amazing breadth of nineteen feet of solid brickwork. In addition to this it is strengthened with numerous arches built into the wall. Three cornices run round the exterior of the rotunda and divide it into three rings, the lowest of which was faced with marble, and the two upper with stucco. The dome springs from the second cornice, and consists first of a ring of masonry seven feet high, and then of six concentric rings, presenting on the exterior the appearance of six steps. The top is flat, and is pierced in the centre with a large round opening twenty-seven feet in diameter. Round the opening is a ring of ornamental gilded bronze, which is the only part of the old bronze gilt roof now remaining. The masonry of the dome is of wedge-shaped pumice stones, chosen for this purpose on account of their lightness. The same kind of stone is used in several other buildings in Rome where lightness combined with moderate strength is required. The exterior of the dome is flat and heavy, and impressive only from its stern and massive solidity. The proportions of the interior are altogether different, and have been universally admired for their elegance, and the exquisitely simple taste with which they are decorated. The lower part contains eight deep niches, alternately semicircular and square, in one of which the entrance doors are placed, while the others were filled with statues of deities, now replaced by Romish altars. They are decorated with pilasters, and two Corinthian columns stand in front of each, supporting the entablature which runs round the whole interior. Between the eight principal niches are eight smaller ones, now used as altars, faced with ædiculæ consisting of two small columns with entablature and pediment. The two ring cornices in the interior answer in position to the lower exterior cornices. Above the upper cornice which runs quite round the building there were originally twelve niches surrounded with elegant marbles and stucco work. These were altered in 1747, and their effect injured by the introduction of heavy pediments, and by the removal of the marbles and stucco work. The interior of the roof is relieved by well-designed rectangular coffer work, decreasing in size towards the apex of the dome so as to give the impression of height and space. The floor is laid with slabs of Phrygian and Numidian marble, porphyry, and grey granite, in alternate squares and circles, set in reticulated work. In the centre it has a depression pierced with small holes to carry off the rain water from the aperture above. This drain probably communicated with the great cloaca built by Agrippa to drain the Campus Martius. The proportions of the interior of the dome are admirably adjusted, so that no part of the building has an undue prominence, contrasting favourably in this respect with S. Peter’s, where the immense size of the piers on which the dome is supported dwarf the upper part too much. The Pantheon will always be reckoned among the masterpieces of architecture for solid durability combined with beauty of interior effect.

The Romans prided themselves greatly upon it as one of the wonders of their great capital, and no other dome of antiquity could rival its colossal dimensions.[93] The height from the pavement to the crown of the dome is 143 feet, half of which is occupied by the cylindrical wall and half by the dome; this height is insignificant when compared with S. Peter’s, the dome of which is 405 feet from the pavement to the base of the lantern, and the exterior appearance of S. Peter’s is far finer, but the diameter of the Pantheon is the greater, and the proportions of the interior more harmonious.

The inscription assigns its completion to the year B.C. 27, the third consulship of Agrippa. For a long time the mistaken notion prevailed that the building was dedicated to Juppiter Ultor, a misapprehension arising from a corrupt reading in a passage of Pliny, where the words Jovis Ultoris had been inserted instead of diribitori. The original name, Pantheon, taken in connection with the numerous niches for statues of the gods in the interior, seems to contradict the idea that it was dedicated to any peculiar deity or class of deities. The seven principal niches may have been intended for the seven superior deities, and the eight ædiculæ for the next in dignity, while the twelve niches in the upper ring were occupied by the inferior inhabitants of Olympus. Dion hints at this explanation when he suggests that the name was taken from the resemblance of the dome to the vault of heaven.[94]

Originally, to all appearance, the Pantheon was not intended for a temple, but for a part of Agrippa’s Thermæ. Its shape corresponds very closely with the description given by Vitruvius of the Laconicum or Sudatio attached to all Roman Thermæ. He recommends a dome-shaped building, with a round opening like that of the Pantheon at the crown, which can be opened or closed at pleasure, so as to lower or raise the temperature, by the removal or application of a lid (clypeum) moved by chains.