Cosimo III in the context of Marguerite Louise d'Orléans

The Basilica di San Lorenzo (Basilica of Saint Lawrence) is one of the largest churches of Florence, Italy, situated at the centre of the main market district of the city, and it is the burial place of all the principal members of the Medici family from Cosimo il Vecchio to Cosimo III. It is one of several churches that claim to be the oldest in Florence, having been consecrated in 393 AD, at which time it stood outside the city walls. For three hundred years it was the city's cathedral, before the official seat of the bishop was transferred to Santa Reparata.

San Lorenzo was the parish church of the Medici family. In 1419, Giovanni di Bicci de' Medici offered to finance a new church to replace an eleventh-century Romanesque rebuilding. Filippo Brunelleschi, the leading Renaissance architect of the first half of the fifteenth century, was commissioned to design it, but the building, with alterations, was not completed until after his death. The church is part of a larger monastic complex that contains other important architectural and artistic works: the Old Sacristy (Sagrestia Vecchia) by Brunelleschi, which has interior decoration and sculpture by Donatello; the Laurentian Library (Biblioteca Laurentiana) by Michelangelo; the Medici Chapels (Cappelle Medicee), two structures that include the New Sacristy (Sagrestia Nuova) based on Michelangelo's designs; and the larger Cappella dei Principi ('Chapel of the Princes') being a collaboration between the family and architects.

Gian Gastone de' Medici (born Giovanni Battista Gastone; 25 May 1671 – 9 July 1737) was the seventh and last Medicean grand duke of Tuscany.

He was the second son of Grand Duke Cosimo III and Marguerite Louise d'Orléans. His sister, Electress Palatine Anna Maria Luisa, arranged his marriage to the wealthy and widowed Anna Maria Franziska of Saxe-Lauenburg in 1697. The couple despised each other and had no children. As Grand Prince Ferdinando, Gian Gastone's elder brother, predeceased Cosimo III, Gian Gastone succeeded his father in 1723.