Piranesi considered the Temple of Jupiter Tonans one of the most splendid examples of ancient Roman architecture. In fact, the previous veduta of this site prominently positions the Temple, which stands at the foot of the Capitoline hill and thus at the “roots” of the Roman Forum, in both its visual design and textual key. The perspective of this and the previous veduta enhances the robustness of the mostly buried building. Even with its few columns surrounded by overgrown vegetation, Piranesi highlights the Temple's solidity, a quality that he admired and used to support his argument for the magnificence of Roman architecture.
In the key’s lengthy expository text, Piranesi equally praises both “the exquisite delicateness and arrangement of the carvings” and the “weightiness and majesty of the structure.” A key term in Piranesi's vocabulary, sodezza, or weightiness, attested to the quality of Roman engineering. For example, Piranesi notes that the columns were astonishingly constructed “from only one piece of marble.” Piranesi argues that these features allowed buildings such as the Temple of Jupiter Tonans to survive for a millennium, even when exposed to the destructive forces of nature (in this case, a fire that almost consumed the entire Forum in the third century). The exaggerated scale of the image further stresses the massive structure of the Temple. Erupting from the ground below, the herculean columns quite literally overshadow the miniscule and unadorned modern buildings on the right. Every minutia of the Temple - cracks and ruptures, delicate vegetal forms of the cornice, the decorative armature in the frieze, individual acanthus leaves of the capitals - is depicted in detail and in high relief. These visual details, brought out by the novel play with chiaroscuro, additionally support his arguments about the significance of ornament.
Rather than occupying a secondary role, the ornamental intagli, or reliefs, that adorn the building are what in fact convey the "majesty" of the Temple. The role of ornament was key point of contention in eighteenth-century scholarly debates about architectural theory, and it is no accident that Piranesi uses the adjective "ornato" here. The so-called rigorists argued that ornament was a distraction, detracting from the nobility and soundness of the basic design of a building. Though the prevailing view, Piranesi took another, more controversial, position. In one of Piranesi's most polemical writings, the Letter to Monsieur Mariette (1765), the artist declares,
"In such art, as in nature, the eyes will not see confusion but a beautiful and pleasing arrangement [disposizione] of things. And, in truth, if the ornaments used in architecture are beautiful themselves, then the architecture will also be beautiful. Why choose to give the eyes a single pleasure, such as that of looking at a piece of architecture, when we can give them the twofold pleasure of seeing it clothed in ornament, since we can see our way to reconciling the two?" (Beamish & Britt 113)
Using the very same terms in the text of the veduta, Piranesi points to how the "exquisite delicateness and arrangement [disposizione]" of the reliefs embody the very grandeur of the Temple itself.
Note: This temple has now been attributed as the Temple of Vespasian, however in Piranesi's day it was considered to be the Temple of Jupiter Tonans. Piranesi dates the site to the time of Augustus.
To see this image in Veduta di Roma, vol 17 of Piranesi's Opere, click here.