Situated in the locality of La Canonica, today a heavily wooded area, is a natural terrace delimited by a ditch, on which stand the remains of the ecclesiastical structure of San Niccolò. An investigation of the published written sources in the State Archive at Siena found what to date is the earliest attestation. This is a document of 1137 regarding the sale of assets by the bishop of Volterra to the bishop of Siena. The canonical church of San Niccolò was not amongst the assets sold to the diocese of Siena, however the silver mines situated close to San Niccolò were ceded to Siena. Therefore, this documents attests the probable role played by the canonical church itself in the silver extraction and management of its working, on a par with the local nobility which controlled the production processes. Topographical investigations carried out in the municipality of Montieri by the University of Siena at the beginning of the 1990s, as part of an undergraduate project coordinated by Riccardo Francovich, highlighted the presence on the site of galena, sphalerite and calcopyrite as well as waste products from metal working processes. On the site’s surface the walls of a church built of small limestone blocks were visible. The main nave and at least two apses were identified. Around the church structure there were several buildings which cannot be definitively identified at present due to the presence of trees. Moreover, in some of the areas adjacent to the site there were dumps of waste materials from the working of coinable metal. In the Middle Ages the territory of the municipality of Montieri was of historical importance due to the presence of the silver mines. The first certain document regarding Montieri mentions the donation made in 973 by Lamberto, son of the Marquise Ildebrando of the Aldobrandeschi counts, to the canonico Ropprado, drawn up in the castle of Gagliani in the municipality of Campagnatico. This act, in which part of the \"corte et castello sito Monterii\" was donated to the church of Volterra, also attests the transformation of Montieri into a castrum as early as the 9th century. In the same century a rural structure named after San Paolo was attested as being built in a place circa two kilometres south-east of the present town of Montieri. Between the 11th and 13th century there was a period of increased exploitation of the mineral resources in the territory of Montieri. In the town itself major changes occurred, with the foundation of a church dedicated to San Giacomo, the construction of the fortification, of several aristocratic palaces and the municipal foundry. During the 14th century the silver mines were gradually exhausted and were ceded to Siena. The study of the Canonica of San Niccolò is one of the many activities that are part of the University of Siena’s long running study of settlement dynamics in the territory of the Colline Metallifere. These include survey, excavation of fortified settlements and the mapping of mining areas. The main aim of these investigations is the study of the birth of the medieval settlement network, in relation to the exploitation of the mineral resources and control of metallurgy production processes.

between the 5th - 30th October 2009. The excavation examined the entire rectory complex, identified during a cleaning campaign in October 2008, which comprised a series of structures of differing plan and size. The complex is situated on a large plateau immediately north-west of the ‘fosso della canonica’ which runs down from the summit of the Montieri hill. The cleaning operation revealed the tops of the walls and scatters of stone across the entire site. In order to gain an understanding of the ecclesiastical settlement’s development it was decided to use a mechanical digger to remove the deep layer of collapsed material obliterating the walls and then continue with a manual stratigraphic excavation in chosen areas. The excavation uncovered a number of buildings belonging to the monastic complex including the church and cloister structures, and a large room situated in the western area of the plateau which was probably used for craft-working activities. Cleaning was begun of the entrance to a mine situated close to the ecclesiastical site. Investigations are still in the initial stages and the complex development of the monastic settlement has still to be fully understood. However, it was seen that the entire complex had very rich architectural decorations such as decorated bricks (very similar to those preserved in the arches of the Le Fonderie building) and limestone and travertine elements such as arches, door jambs, quoins and brackets. This evidence attests the substantial investment that the bishop of Volterra had made in the foundation of this complex, on a site that was crucial for the overseeing of the important and profitable silver mines which must have provided precious metal for the nearby Episcopal mint situated in the borgo of Montieri in the Le Fonderie building. The church was situated in the easternmost area of the complex. It had a single nave and a hexagonal apse with a central plan and three apertures. There was evidence of rich architectural decoration such as arches built of decorated bricks and large quantities of travertine and limestone architectural elements found within the excavated layers of collapse. The particular plan, unique for this territory, and the high quality of the structures, again highlight the employment of specialist artisans by the bishopric of Volterra. The complex, as well as controlling the production process (the presence of the mine entrance close to the ecclesiastical settlement is significant) also had the function of displaying the wealth and power of the bishopric of Volterra to the workers, mostly miners and foundrymen passing in front of the church before entering the mine, and also to the general population of Montieri.

The second campaign at the Canonica di San Niccolò took place between the 30th August and 29th October 2010. The investigations continued in the area of the church, cloister, the two buildings and the external area in an attempt to investigate the site’s various phases, which had only been partially identified by a study of the standing remains. At the end of the second campaign, the layout and structures uncovered indicated the existence of phases predating those attested in the documentary sources. Throughout the life of the complex, the main buildings maintained the original positions due to the close connection with the mining resources. Thanks to the reconstruction of the spaces for the period investigated by the excavations (12th to 13th century), a clear division was noted between the central nucleus, the Canonica di San Niccolò, the ecclesiastical settlement itself, and an external craft-working area, adjacent to the site but physically separated from it by the cloister enclosure wall. The activities undertaken in this period in the buildings, in particular in the room bordering the cloister to the east and in the only covered room in the external area, provided more information. In both cases, the activities involved the working of minerals extracted from the surrounding mines. In fact, the production structures excavated in 2010 in the external craft-working area date to this period, in particular a furnace for the reduction of lead and other structures built in brick and clay, including a number of small clay-lined channels, one of which similar to those excavated inside the foundry building.

This campaign continued the excavations inside the monastic complex and, at the same time a survey was undertaken on the summit of the Montieri hill. The survey identified another important part of the activities linked to the exploitation of mineral deposits, the areas used for making the charcoal that was indispensible for fuelling the furnaces. The excavation results made it possible to lengthen the settlement’s chronology known from documents and make an accurate description of the activities undertaken within it. In fact, it was possible to subdivide the history of the site into four periods. The first, still not fixed, certainly predates the 11th century, in which the first occupation of the plateau was attested by a high-status female burial. At the moment, this cannot be linked with any other evidence, but the veneration of the individual clearly continued until the successive period, given that the church dating to the first phase of the canonica was built so that the stone coffin was situated at its centre.