The San Martino Plain is an archaeological site in Pianello Val Tidone, on the edge of the two valleys formed by Chiarone and Rio Tinello streams.
It is a complex settlement located on a plain defended by steep slopes, about 512 metres above sea level. Men completed the existing natural defence with a wooden structure, as documented by the holes in stones along the perimeter of the settlement.
Between 1991 and 1998 protohistoric materials were discovered, dated between the end of the Bronze age and the Iron age. They were found on the western side of the encampment, where a landslide collapsed from the plain above. Remains from a late-antique building in stones and mortar, founded on rock, which attached pre-existing levels have been discovered on top of the cliff. In 1998 another cultic building was found, with remains of burials that could be dated from the late-antique period.
Since 2000 a series of surveys have been carried out by the Superintendency of Archaeology, which allowed to outline the settlement timeline of the site along two periods: the first during the pre and proto-historic era, with materials that could be dated to the Bronze age and the second Iron age. The second began from the late-antique era and continued throughout the Middle Ages.
The analysis on ceramic artefacts show that the presence of man dates to an initial settlement in the late Bronze era, lasting until the Iron age. The research carried out until today did not show any trace of further inhabitants between this first phase and the late-antique era, a period when the site was again inhabited to thrive through the Middle Ages. Only the cultic building was used until the 17th century.
Excavations have been carried out by Associazione Archeologica Pandora under the supervision of the Superintendency of Archaeology of Emilia-Romagna region. They brought to light a house with two rooms, an oven, a large cistern and a religious area with a necropolis and a church for cult open until the Renaissance.
The church presents a unique plan made of several niches, and points to the east. Thanks to the analysis of coins, it is possible to state that the church was used between the 12th and the 13th century.
In 2011 the archaeologists found an apse in the church originally dedicated to St. George, pointing to south-west, around which were located some tombs without grave goods. The same orientation was found for other tombs under a late-antique building close by. They seem to belong to the most ancient building phase of the church that can be documented up to today, which originally had a different orientation compared to the last cultic phase in the 16th century. The stratigraphic context seems to connect the tombs with the Longobard phase of the site, attested by a hut built on the remains of a late-antique building where over the past few years have been found tools and weapons (intact or fragmented) from the Longobard era, like a bearded axe.
This hut probably served as workshop for a blacksmith: there was a crucible, slag and other broken or fragmente objects that may have been used to create other tools. The original settlement of artisanal workshops had been put under scrutiny in the campaigns between 2013 and 2015, which brought to light other iron working tools and a glass goblet similar to those found in Longobard tombs from the end of the 6th-beginning of the 7th century.
The materials from San Martino plain can be seen in the Archaeological Museum of Val Tidone in Pianello Val Tidone.