The drawing represents ornamental details, now lost, from the Castel Sant’Angelo, originally the Mausoleum of Hadrian, as is indicated by the label. The monument is situated on the far bank the Tiber in the north-western part of the city, and it is reached by the Aelian Bridge (replaced by today’s Ponte Sant’Angelo), which was constructed in 134–39 CE (LTUR Suburbium, 1, pp. 15–22; Mercalli 1998). The drawn details are of the base and capital of a corner pilaster and the corner of the entablature, which originally adorned the massive square podium beneath the mausoleum’s enormous drum.

Little of the podium’s decoration survived into the sixteenth century and what did is represented in a topographical drawing in the Codex Escurialensis (fol. 30v), which shows that only the southwest corner had its pilaster and entablature still intact. The capital was of an unusual Corinthian type being very broad in relation to its height and having acanthus leaves only at the left and right extremities with a tendril and scrolls between and egg-and-dart decoration at the bottom. It supported a three-fascia architrave and then a frieze of garlands draped over bucephala with paterae above (a small portion of which still survives), and finally an elaborate dentillated cornice. The entablature broke forward over the pilaster, not shown in this drawing but recorded in another one in the Codex Escurialensis (fol. 25r), and the portion of the frieze above it actually accommodated three bull’s heads, one in the centre and two at the corners (Strong 1953). The capital in the Coner drawing is not depicted, therefore, to the same scale as the entablature, even though they look as though they are of a piece (like in Fol. 53v/Ashby 92). It may be that the draftsman realised his error and for that reason decided to treat the two elements rather separately, the fascias of the architrave not being inked in, even though the black chalk underdrawing is visible. The base and capital of the pilaster are then shown with the shaft between them almost completely elided (a small dividing line indicating that the shaft was slightly wider at the bottom than at the top). The base sits on a double plinth and consists of a torus, an astragal and a cavetto. The cavetto might be interpreted from the Coner drawing as the apophyge of the shaft above, with the shaft then tapering towards the top, but this is not the case, as is clear from an unattributed drawing in the Uffizi, which shows the cavetto very clearly. Despite disparities of scale, the pilaster and entablature are otherwise recorded more accurately than they are in the Codex Escurialensis (fol. 25r), where there are bucrania rather than bucephala in the frieze, or in Giuliano da Sangallo’s Codex Barberini, where the frieze is depicted as being almost concave.

The Coner drawing is unlike many others of details in the codex in being executed freehand as well as in following different representational conventions, but, in these respects, it is consistent with it having been produced during the second phase of the compilation’s execution.

OTHER IMAGES MENTIONED: [Anon.] El Escorial, Real Monasterio, 28-II-12 (Codex Escurialensis), fols 25r and 30v (Egger 1906, pp. 88 and 94); [Giuliano da Sangallo] Rome, BAV, Barb. lat. 4424 (Codex Barberini), fol. 17v (Hülsen 1910, p. 28; Borsi 1985, pp. 111–12); [Anon.] Florence, GDSU, 4330 Av (Bartoli 1914–22, 6, p. 111)