Rome arrived at the zenith of architectural science, such as it was, under the reign of Augustus, as Athens attained infinitely superior honors under Pericles. But, with the single exception of Trajan, not one epoch after that great exponent of his age was marked by structural magnificence erected by Romans. When Virgil, Homer, Cicero, and Livy, were publishing their works, the metropolis was graced with a number of gorgeous temples; but the decline of letters and arts soon followed, and architecture, especially, sunk to the last degree. The Parthenon and the Pantheon, those two great types of their respective ages, might be compared on the score of magnificence, but they were utterly devoid of resemblance as masterpieces of art. The quadrangular portico of the latter may be presumed to have been intended to signify the union of architectural powers; without some such reason the rectilinear front would not have been stuck before a circular edifice, and the egregious anomaly can be accounted for on no more plausible ground. That Rome bore the arts, as she did the spoils, and even the gods of conquered nations, to her own haughty abode, is true; but it is not less evident that she was destitute of all the arts and elegances of high civilization till she imported them from Greece, and that she had neither definite principles, nor correct artistic conceptions, of her own. The celebrated temple of all the gods to which we have just referred, is supposed to have been erected in the time of the Republic, and that the portico was appended A.D. 14, by Agrippa. Of all the temples of the Romans, the Pantheon is by far the most original and typical, and as a rotunda it is unmatched in the ancient world. There is a simplicity about its proportions, the height being exactly equal to the width, and in the mode by which it is lighted through a single aperture in the roof, which gives it a character of grandeur that redeems the clumsiness of detail, which would nearly spoil any edifice less grand in conception. That majestic dome is the only Roman structure extant that has power to carry the mind beyond the imperial mass of crime out of which tower the splendors of the Augustan age, and tells us of that grand old Republic whose glory elicited the worth and illuminated the figures of subsequent history.