The beautiful basilica of Santo Spirito is one of the most evocative spiritual places in Florence. In the mid-13th century, Florence had a considerable increase in population that affected the areas inside and outside the walls. With the construction of the Santa Trinita Bridge, the area called Oltrarno became an integral part of the city. The Augustinian Convent located there became an important institute of theological and philosophical studies, so much so that it was necessary to build a new square, that of Piazza di Santo Spirito, to accommodate the crowd attending their sermons. The convent was frequented by important scholars of that period, including Robert of Anjou and Giovanni Boccaccio, who left his personal library to the Augustinians. At the end of the 1300s, friar Luigi Marsili, friend of Petrarca and Coluccio Salutati, formed one of the first Literary Academies in the city, welcoming Leonardo Bruno, Poggio Bracciolini, Giannozzo Manetti and other frequent visitors to the Convent. Around 1434, the construction of a new basilica was entrusted to Filippo Brunelleschi, who had already worked in Oltrarno at San Jacopo and Santa Felicita. In his original project, Brunelleschi wanted the facade of the church and the square to face the Arno river: this was not possible as it would have been necessary to buy the adjacent properties and not everyone was willing to sell. In Brunelleschi's project, the sides of the church were to be supported by a loggia similar to that of the Spedale degli Innocenti, but the project was not successful. In 1446, Brunelleschi died and the basilica's construction site passed under the direction of Antonio Manetti, Giovanni da Gaiole and Salvi di Andrea. None of them fully understood Brunelleschi's project and significant changes were made. For the maintenance of the original project, authoritative individuals made their voices heard, such as mathematician Paolo dal Pozzo Toscanelli and Giuliano da Sangallo, as well as that of Lorenzo the Magnificent. After Lorenzo's death, a seventeen-year-old Michelangelo lived in the convent, with the complicity of the Prior, and was able to study the anatomy of the corpses. It was thanks to this experience that Michelangelo became unbeatable in portraying the human body in great detail. To thank the Augustinian friars, Michelangelo left the Crucifix, a work that is now located in the sacristy.
The inside of the church is very similar to the basilica of San Lorenzo: majestic columns divide it into three naves and surround the main altar. The coffered ceiling was not part of Brunelleschi's original project. His idea had been to leave the ceiling open, in order to give the idea of a connection with the sky. The inside of the church is very simple and contains works of art by great Renaissance artists. The basilica has two cloisters: one is the Grand Cloister and the other is known as the Cloister of the Dead, thanks to the large number of tombstones that crowd its walls.