A large architectural drawing by Michelangelo showing an early proposal for the façade of Florence’s Basilica of San Lorenzo is on public display at Palazzo Corsini as part of the 34th Biennale Internazionale dell’Antiquariato di Firenze (BIAF).
The work, known as the Primo progetto per la facciata di San Lorenzo — First Project for the Façade of San Lorenzo — belongs to the collection of Casa Buonarroti, the Florence museum devoted to Michelangelo and his family. It can be seen at Palazzo Corsini until 4 October, when this year’s Biennale ends.
Its appearance at BIAF comes shortly before a new conservation treatment. The project is being funded by Fondazione CR Firenze, while the restoration will be carried out by Florence’s Opificio delle Pietre Dure (OPD), one of Italy’s leading state institutes for the conservation and study of works of art.
What examinations have revealed
Before the exhibition, the drawing underwent diagnostic investigations at the Opificio delle Pietre Dure laboratories at the Fortezza da Basso in August.
The preliminary examinations have provided new information about the way Michelangelo developed the design. According to material released for the exhibition, an initial trace, probably made with silverpoint, was followed by pencil and then ink. Researchers have also identified different types of ink, which are now being studied.
The sheet itself also tells a complicated physical story. Its lower section consists of four sheets of paper and is lighter and better preserved, while the upper section is made from two darker sheets without watermarks. The findings will help conservators determine how to approach the treatment after the Biennale.
The work is particularly delicate because it is one of the larger drawings in the Casa Buonarroti collection and was historically among those selected for display. Repeated exposure over previous decades contributed to its deterioration, according to the material accompanying the project.
The façade Michelangelo never built
The drawing belongs to one of the most important unrealised projects of Michelangelo’s career.
San Lorenzo, closely associated with the Medici family, still has the unfinished bare exterior that visitors see today. The idea of giving the church a monumental façade took shape following the visit to Florence of Pope Leo X, Giovanni de’ Medici, in 1515.
Several leading Renaissance artists were involved in the competition for the commission, including Raphael, Jacopo Sansovino and members of the Sangallo family. Michelangelo initially appears to have been considered principally for the sculptural decoration, but by 1516 he had secured responsibility for the architectural design as well.
His plans developed through several stages. Casa Buonarroti preserves three drawings documenting this evolution as well as the large wooden model produced around 1518, measuring more than two metres across.
Michelangelo eventually conceived the façade as a monumental architectural structure largely independent of the shape of the church behind it. Columns, pilasters, niches and sculptural elements would have transformed the exterior into an elaborate setting combining architecture and sculpture.
A contract between Michelangelo and Leo X was signed on 19 January 1518. The commission subsequently became entangled in difficulties involving the sourcing and transportation of marble, including the decision to use quarries around Pietrasanta rather than the established Carrara quarries.
The project was never completed. Casa Buonarroti records the cancellation of the marble-supply contract in March 1520, although evidence indicates that some activity connected with the project continued into 1521. Later attempts to revive the plan also came to nothing.
Michelangelo nevertheless continued to work on the San Lorenzo complex, producing two of its defining Renaissance spaces: the New Sacristy and the Laurentian Library.
Practical information
The Michelangelo drawing is displayed in the Salone del Trono at Palazzo Corsini during the 34th Florence International Antiques Biennale. The BIAF is open to the public from 26 September to 4 October 2026, daily from 10.30 a.m. to 7.30 p.m.
After the exhibition closes, the drawing is due to return to the Opificio delle Pietre Dure for the conservation work funded by Fondazione CR Firenze.
BIAF official programme and visitor information
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