Together with Santa Croce, Santo Spirito and Santa Maria Novella, it is one of the “great basilicas” of Florence, founded according to the tradition by Saint Ambrose – the first bishop of Milan – in the fourth century AD: it is therefore one of the oldest churches in the city. Its current appearance, however, is the result of the last major reconstruction work that took place in the 15th century at the wishes of the Medici and under the direction of the great architect Filippo Brunelleschi. Its bare stone façade was intended to receive a rich marble decoration designed by Michelangelo, which unfortunately was never executed. The interior is a masterpiece, also embellished by sculptures of rare expressive intensity made by Donatello .

Since 1869 the Medici Chapels have been a state museum, but their history is closely associated with that of the Basilica di San Lorenzo, of which they are part. The museum consists of the New Sacristy, designed and conceived by Michelangelo, the Chapel of the Princes, a monumental mausoleum built using semi-precious stones, the Crypt, where the Medici Grand Dukes and their relatives are buried, and the Lorenese Crypt, which contains the funeral monument to Cosimo the Elder.