Giuliano's first major, independent commission came from the Medici family and it showed not only his architectural skill, but also his knowledge of defensive fortifications.
Lorenzo the Magnificent called upon Giuliano to build military fortifications and manage the artillery in the town of Castellina against an invasion led by the Duke of Calabria.
In this role, Giuliano successfully pushed out the Calabrian forces and showed his natural talent for military building and strategy.
[5] In 1484, a child from the town of Prato claimed to have seen a painting of the Virgin Mary and an infant Jesus come to life on the side of the public jail.
Santa Maria delle Carceri was commissioned after the townspeople declared this a miracle and decided that a church should be built at the site of the vision to commemorate it.
[1] This is a classical layout design that features four arms of equal length extending off of a central nave and it had not been used extensively in the Renaissance before that point.
[1] In 1488, after the initial plans were set for the villa in Poggia a Caiano, Lorenzo de' Medici commissioned Giuliano to build a castle for Ferrante of Aragon, the King of Naples.
[6] The building of the castle was part of a larger political plan that the leaders of the different city-states of Renaissance Italy engaged in.
When city-states were not warring with each other, they would send gifts as well as painters, sculptors, and architects to each other as diplomatic displays of good faith.
Additionally, by sending Giuliano to Naples, the Medici family was attempting to export Florentine culture and architecture across the Italian Peninsula.
[6] After Giuliano completed his service for the king, he was sent back to Florence with gifts including money, paintings, and sculptures.
[11] Shortly after Giuliano completed his work on Santa Maria delle Carceri, his patron and longtime friend Lorenzo died in 1492.
[12] After the death of Lorenzo the Magnificent, a power vacuum was created that allowed an opportunity for France to invade Florence in 1494.
Two years previously, the Bishop of Ostia, Giuliano della Rovere, had fled Italy after his rival in the church, Rodrigo Borgia, was elected Pope as Alexander VI in 1492.
Using the shared exile and his past history as a patron of architecture, he convinced Sangallo to design a palace in Savona, France for him.
[12] The palace design was greatly influenced by the Bishop's other estates such as the one in Vincoli and the fortress in Ostia that Sangallo helped renovate.
[2] Giuliano was called by Julius II to help Michelangelo remove mould from the Sistine Chapel ceiling after the younger artist had applied too wet a plaster.
Giuliano's legacy is unlike other architects of the era, because many of his largest works remain either unfinished or are no longer standing at all such as Santa Maria delle Carceri, Palazzo Gondi, and the Church of San Gallo.