Vestibule

In architectural terms, the vestibule represents the most elaborate part of the edifice. It takes the form of a square whose walls soar high above the observer. They are divided into three branches, each of which is flanked on the main story by pillars which are deep-set in the wall. This leads to the peculiar result of twin pillars, deeply recessed, which scarcely seem capable of bearing the ledge above which the clerestory is situated. The richly gilded and ornamented wooden ceiling obviates the necessity for a vault.

The vestibule's function was to house the stairs bridging the level between the upper cloister and the reading room (see fig.). After experimenting with double-ramp stairs like those of the Villa Medici at Poggio a Caiano, and with combinations of convex and concave as at the Vatican Belvedere, Michelangelo hit on the notion of three flights meeting and fusing into one at a central landing. The central flight is a series of 'overlapping oval boxes' as Michelangelo himself wrote of it, flanked by side 'wings' (for servants when the central flight was being ceremonially used). As built by Ammanati, the stairs diverge slightly from Michelangelo's intentions, but retain the flowing, dream-like invention evident in his description. The vestibule has been seen as the epitome of Michelangelo's Mannerist architectural style.

View the plan of the San Lorenzo ensemble, Florence.