This article analyses a Latin satire in Horatian style published in 1763 by Fabio Devoti. The subject of the satire is Roman architecture. The text comprises a conversation between a Roman and a presumed foreigner that takes places during a walk through the Forum to the Colosseum. In appearance, it would seem to be a canonical comparatio between the architecture of the ancients and that of the moderns. But Devoti’s satire was written during a critical moment in eighteenth century Roman culture: it was published a year after the inauguration of the Trevi Fountain, two years after the publication of Piranesi’s De Romanorum magnificentia et architectura and one year after Winckelmann’s Osservazioni sull’architettura degli antichi. The satire is in reality a defence of traditional classicism, which opposes Roman culture, of which the great periods of Italian artistic culture (those of Michelangelo, Bernini and the Salvi of the Trevi fountain) were considered to be heirs, to the emergent neoclassicism, which decisively devalued the Roman model in favour of the Greek. The article reconstructs an important part of the debate on ornament in architecture, allying with such figures as Bottari, Lione Pascoli, Frézier, Laugier and Lodoli among others, recuperates one of the best descriptions of the Trevi Fountain from the morrow of its inauguration and provides a contribution to the controversial problem of the cultural humus on which Piranesi’s artistic fortune flourished.