Adjacent to the church is the former Augustinian convent.
Built starting in the middle of the thirteenth century, it was characterized by a single cloister surrounded by the chapter house, the dormitory, and the refectory, in accordance with the four-sided pattern typical of Augustinian structures.
Despite its modest size, as early as 1300 it must have played a role of primary importance if, at the time, it was the seat of one of the five-year courses of preparation for teaching, know as “Studia Generalia,” for the friars who would go on to teach in the Provinces of the Order.
Between 1500 and 1600 the structure was affected by construction work such as the building of the new chapter house after the old one was destined for use as a private chapel by the noble Piccolimini family of Siena, and the construction of a second cloister and another group of buildings around it to hold a dormitory, refectory, and infirmary.
In the last years of the seventeenth century the new library was built; the painter Apollonio Nasini was assigned the task of decorating it.
In 1798 the complex was damaged by the violent earthquake which shook the city. As a result, a restoration project was implemented under the guidance of the Sienese architect Francesco Paccagnini.
As a result of Napoleon’s suppression of convents in 1808, the decision was made to transform the convent buildings into a high school, assigning the work of renovation to the architects
Agostino Fantastici and Lorenzo Turillazzi.
With the fall of the French government in 1814 this idea was abandoned, and two years later the complex was bought by the Scolopian Fathers, who had already for some time been providing the teaching of the students at the Collegio Tolomei, an institution founded in 1676 at the behest of the nobleman Celso Tolomei for the purpose of educating the sons of the aristocratic families in Siena and its territory. Thus Fantastici was engaged once again, this time to adapt the former convent for use as a boarding school. The work, which involved adding another story, dividing the largest spaces into smaller rooms, and building an interior monumental staircase, with the upper floor devoted to large dormitory rooms and the lower floor containing the service areas and common rooms, was brought to a close on 10 November 1820 with a formal inauguration.
Since then, the history of the former Augustinian convent is indissolubly tied to that of the Collegio, which, after being turned into a national boarding school in 1883, occupied the complex until its closing in 1997.
Currently, the space houses a public high school.