The 2015 campaign provided more information about the building’s history, documenting unknown elements regarding its chronology, development of its plan and original function. The small single-apsed building kept the same alignment throughout its life (apse facing east), but underwent various alterations to its plan. The first two phases (11th-12th century) are only partially known, as only attested by fragmentary parts of the apse and walls (phase 1) and by the apse and several stretches of the nave (phase 2). The latter, was characterised by a construction technique that used squared marly-limestone blocks arranged in regular courses. In the 13th century, the structure was rebuilt, probably by a specialist workforce (magistri Antelami), using stone blocks that were squared and flattened on the outer face, arranged in regular courses. Although the apse, built directly on top of the earlier one, is standing because it remained in use until the final construction phase, excavation was necessary to uncover most of the nave’s perimeter walls. The church underwent substantial rebuilding on two more occasions: in the late medieval period, when the nave was completely rebuilt, and in the 17th century, with the drastic reduction in size of the nave.

The excavations led to the identification of 40 graves, 39 of which single burials, while one (t.34) contained three individuals all buried at the same time. It is possible that the skeletons in what have been identified as two separate graves (t. 40, t.41) were buried at the same time. A total of 40 individuals were found, 26 adults, 11 infants and 3 adolescents. The 26 adults, of which 15 male, 9 female and 2 indeterminate, include individuals from all adult ages: 4 young adults, 3 mature, 2 elderly and 5 indeterminate.

Some preliminary considerations can be made about the distribution by sex and age of the individuals. Firstly, burials of sub-adults and females are always present in the 9th and 15th-16th centuries, while male individuals, in addition to infants, appear between the 14th and 15th centuries. Both sexes only appear in the 13th century, which corresponds with the phase having the largest number of depositions (14 individuals).

Tomb13 is an interesting case, an “anomolous” burial with an individual (an elderly female) placed with the head to the north in a prone position, the arms folded below the torso and the legs bent.
The excavations at the site of S. Stefano are of fundamental importance for the understanding of territorial and population structure in the northern Scrivia valley between the late medieval and modern periods.