The University of Siena has been excavating on Poggibonsi, a flattened elongated hill, since 1991. Life in the territory began in the late Roman period and continued throughout the early medieval period and, after an apparent interruption, resumed between the mid 12th and the beginning of the 14th century. During this period the site was the historic centre of Poggibonsi: between 1155 and 1270 a castle stood here, followed by the urban nucleus of Podium Bonzi, and in 1313 it was chosen by Emperor Arrigo VII as the site for the new city of Monte Imperiale. In the 15th century, by order of Lorenzo the Magnificent, a great fortress was constructed on the hill by Giuliano di Sangallo.

The 2006 campaign investigated an area inside the church, this led to the establishment of almost the entire perimeter of the building. Excavations were undertaken to look for traces of the western perimeter wall, which turned out to have been totally robbed, including the foundations. It was possible to follow the line of the fill in the robber trench, damaged by modern agricultural operations. The northern perimeter wall, partly investigated in previous campaigns, was almost completely removed in the modern era. Traces were found of the robber trench of the church façade and consequently a reconstruction of the building’s complete plan was made. Between the pilasters dividing the central nave from the south nave the remains came to light which may be attributed to a wall that delimited an enclosed space, for religious use, within the ruined building. It may be suggested that at least in part the building continued to function as a cemetery and for the celebration of religious functions, as attested by two masonry built loculi, datable to between the 17th-18th centuries, found in the south-west part of the central nave during earlier excavations.

Numerous tombs were also excavated; in some cases showing several phases of use; a total of 36 individuals were identified. A first group of burials comprised tombs situated in the south nave along the perimeter wall. These were infants buried in coffins lined with small limestone slabs, some of which with covers. All the excavated skeletons, except one, were orientated with the head to the south-west. a second group was also situated in the south nave, in the zone between the pilasters and south wall. These were adults buried in earth graves, all (except one), with the head to the north. There were no elements to provide dating. The third and fourth groups are infant burials. It is probable that the three groups of infant burials can be attributed to diverse phases of the building’s use. Those of the third group, situated in the central nave, are situate on the same level as those of the first; the skeletons buried in stone lined coffins were nearly all on the same alignment (head to the south-west). The fourth group of burials, placed around a loculus that does not pre-date the construction of the church, appear also contemporary with the previous group and attributable to a period between the 12th and 13th centuries.