Ichnographia Templi Divi Petri Romae In Vaticano Ex Esemplari Michaelis Angeli Bonaroti Florentini
A 1669 plan by Étienne Du Pérac, after a design by Michelangelo, of the basilica of St Peter's in the Vatican, Rome, printed for architectural study and published by Heidelberg University Library. The sheet shows a centralised cross-shaped ground plan drawn in grey tones with a thin border of printed text along the left edge. A designer could take from it the clean symmetry of the radial layout and the way repeated pier and niche forms build a monumental church plan.
