Ammianus Marcellinus Res Gestae 16.10.14

[14] For he did not (as in the case of other cities) permit the contests to be terminated at his own discretion, but left them (as the custom is) to various chances. Then, as he surveyed the sections of the city and its suburbs, lying within the summits of the seven hills, along their slopes, or on level ground, he thought that whatever first met his gaze towered above all the rest: the sanctuaries of Tarpeian Jove so far surpassing as things divine excel those of earth; the baths built up to the measure of provinces; the huge bulk of the amphitheatre, strengthened by its framework of Tiburtine stone, ¹ to whose top human eyesight barely ascends; the Pantheon like a rounded city-district, ² vaulted over in lofty beauty; and the exalted heights which rise with platforms to which one may mount, and bear the likenesses of former emperors; ³ the Temple of the City, ⁴ the Forum of Peace, ⁵ the Theatre of Pompey, ⁶ the Oleum, ⁷ the Stadium, ⁸ and amongst these the other adornments of the Eternal City.