The light, as we have before observed, is admitted only by a circular opening in the dome, which is twenty-eight feet in diameter[180]. Through this aperture a flood of light diffuses itself over the whole edifice, producing a sublime effect, but only showing all its beauties by permitting every passing shower to deluge its gorgeous pavement. The rain is carried off by a drain to the Tiber; but from the low situation of the building in the Campus Martius, the waters of the Tiber, when it is swollen, find their way up the drain, and flood the interior. Myriads of beetles, scorpions, worms, rats and mice, may then be seen retreating before the waters, as they gradually rise from the circumference to the centre of the area, which is a little elevated above the rest of it. “A beautiful effect,” says Dr. Burton, “is produced by visiting the building on these occasions at night, when the moon is reflected upon the water, through the aperture of the dome.” “The Pantheon retains its majestic portico,” says Mr. Eustace, “and presents its graceful dome uninjured; the pavement, laid by Agrippa, and trodden by Augustus, still forms its floor; the compartments and fluted pillars of the richest marble, that originally lined its walls, still adorn its inward circumference; the deep tints that age has thrown over it, only contribute to raise its dignity, and augment our veneration; and the traveller enters its portal, through which twice twenty generations have flowed in succession, with a mixture of awe and religious veneration. Yet the Pantheon itself has been ‘shorn of its beams,’ and looks eclipsed through the ‘disastrous twilight of eighteen centuries.’” Augustus dwelt at first[181] near the Roman Forum, in a house which had belonged to the orator Calvus; afterwards on the Palatine, but in the moderate house of Hortensius, which was not conspicuous, either for extent or ornament; it had some porticoes of Alban columns, and rooms without any marble or remarkable pavement. For more than forty years he occupied the same chamber, in winter and in summer; and although he found the city by no means favourable to his health in the winter, yet he constantly passed the winter in it. After the palace had been accidentally destroyed by fire, Augustus had it rebuilt, as we are told, and ordered it to be entirely opened to the public. This edifice was called Palatium, from the name of the hill on which it stood; and that being afterwards applied to the residence of the Roman emperors, it has passed into most of the languages of Europe, as the common appellation of a princely mansion.