Zahl, Mass und Massbeziehung in Leon Battista Albertis Kirche San Sebastiano zu Mantua (review)

Designed by Leon Battista Alberti (1404–72), the church of San Sebastiano in Mantua presents an interpretive Gordian knot to architectural historians attempting to tease out the humanist's original intentions from the tangled evidence of its building history. From the initial commission by Ludovico Gonzaga in 1460 until its consecration in 1529, it is generally unclear how faithfully Alberti's plans were respected; and in 1925 the Mantuan architect Andrea Schiavi executed a notorious "restoration" of the building as a war memorial. Following the labyrinthine trail of the historical evidence, Böchmann proceeds both methodically and cautiously in a series of five chapters.

Chapter 1 reviews the features and measurements of the present-day structure, which was again "restored" in 1994. Chapter 2 evaluates the celebrated drawing by Antonio Labacco, dating from around 1530, which Böchmann regards as our earliest reliable evidence for the humanist's original intent. Analyzing it in terms of criteria outlined in Alberti's books on architecture — lineamenta, numerus, finitio, collocatio — she concludes that its ground plan ("di mano di messer batista alberti") derives from an Albertian drawing, but that its elevation is Labacco's own sketch, and that its Italian text is based, with some inaccuracies, on Latin notes by Alberti. In any event, Labacco's sketch presents a symmetrically oriented church featuring a monumental portico (like that of Sant'Andrea) and surmounted by a cupola (like the one planned but not built on Alberti's Tempio Malatestiano, as shown on a medallion by Matteo de' Pasti). But soon after 1460 events necessitated changes in Alberti's original design and in the subsequent building campaign.

Chapter 3 examines the alterations that Alberti made in his original plan soon after construction was begun in 1460, when a basement or crypt was introduced in response to flooding problems and a consequent landfill operation. Construction was halted in 1462, and resumed sporadically thereafter, with Fancelli acting as the agent of Alberti, who was only briefly present at the site in 1463 and 1470.

Chapter 4 recounts how San Sebastiano was eventually completed between 1488 and 1529, largely at the instance of Francesco II Gonzaga. Given the complexity of the building campaign, a (partly conjectural) timeline may be useful:

1460 — Ludovico Gonzaga commissions Alberti's design, with Luca Fancelli as overseer.
1462 — Flooding and attendant problems interrupt construction.
1463 and 1470 — Alberti visits the site.
1472 — Alberti dies in Rome.
1478 — Ludovico Gonzaga dies.
1479 — Federico Gonzaga has Fancelli complete the stone cornices on the portico.
1488 — Francesco II Gonzaga assigns the church to Lateran canons of San Ruffino.
1496–1506 — Francesco II presses the canons to finish the church.
1529 — San Sebastiano is consecrated.
1783 — The Lateran canons are secularized.
1883 — The church, in danger of collapsing, is assigned to the civil authority Genio Militare, which restructures the upper portico and the central vault.
1925 — Andrea Schiavi "restores" church as war memorial.

Chapter 4 ends with a discussion of the fresco, now lost, that once graced the façade. Böchmann argues that the fresco offered a visual parallel to Mantegna's 1496 Madonna della Vittoria (Paris, Louvre) in celebrating Francesco Gonzaga's victory at Fornovo by placing the Mantuan ruler in the protective company of Mary and various saints.

Chapter 5 returns to the proportional analysis of the building as "reconstructed" using Labacco's drawings (plates 74–75). The result is an impressive tabulation of the basic proportions (2:3, 2:5, 3:5, and especially 5:6) that Alberti presumably used in laying out his original design. Böchmann attributes Alberti's frequent use of the ratio 5:6 to symbology connected with Ludovico Gonzaga, who was born on 5 June (5.6) in 1412. Since his birth took place on a Sunday, Gonzaga adopted the sun as a personal device — a symbol that once...