A plan of the Oratory of the Holy Cross, demolished by Sixtus V in 1588. A. Noach connects this sheet with Plate 4 in the copy of Labacco’s Libro in the Royal Collection (unpublished notes, compiled 1947–60). However, this is Lafréry's 1568 edition, reprinted by G.B. de’ Rossi in Rome between 1640 and 1672, which includes the engraving of the oratory published separately by Lafréry as a Speculum print (T. Ashby (ed.), La Campagna romana al tempo di Paolo III: mappa della Campagna romana del 1547 di Eufrosino della, 1914, p.306). Nonetheless, some connection between Labacco and Lafréry is not out of the question. Noach notes that the main measurements of the drawing are identical with the engraving, though there are some differences, such as the wider entrance. The drawing errs in showing the exterior of the oratory as square rather than following the hexagonal shapes of the corner chambers. The top right of the drawing shows corrections, which bring it closer to the engraving. Whether there was any collaboration between Lafréry and Labacco is not known. C. Hülsen wrongly states that the drawing is a copy of Giuliano da Sangallo’s plan in the Barberini Codex, probably misled by the other drawing on the mount, which is one of the copies after Sangallo (Hülsen, Il libro di Giuliano da Sangallo..., vol. I, 1910, p. 46).

The presence of diagonal hatching links this drawing to RCIN 910826, 910831, 910837 and 919256, and is further discussed, along with the attribution to Italian Hand ‘A’, in dal Pozzo A.IX, pp.142-3

The oratory was built for a relic of the True Cross by Pope Hilarus (461–8). Its opus sectile wall decoration made it a popular subject with Renaissance draughtsmen.

Text adapted from Ian Campbell, The Paper Museum of Cassiano dal Pozzo: A Catalogue Raisonné. A.IX: Ancient Roman Topography, 2004, cat.37.