The complex of San Rabano Abbey, situated between Lecci Mount ( Poggio Lecci ) and Alto Mount ( Poggio Alto), was indicated at the time it was being built, at the beginning of the seventeenth century, as Monasterium Arboriense or Monasterium de Arboresio or Alberese. The construction work of the Abbey terminated in 1587. The complex, dated back to the beginning of the eleventh century as a Benedictine settlement, reached the highest point of development during the following century by the Benedictine Cistercians. The choice of the location was in relation to a plan of territorial control, of utilization of the resources, and economical development. Not far from the Abbey was the Queen’s road ( Strada della Regina), which linked the old Aurelia and the sea.

The first document concerning the abbey which we know is dated the 7th of April 1101 and it is the resolution given by the Pope of a disagreement between Roselle Bishop and the Abbot for what concerned the collection of church tithes from the first on the territory of the second. On this document the monastery is indicated probably as a building that was still being constructed, and not yet completed. The growth and importance of the Abbey have developed after 1101: in the successive years, San Rabano reached the maximum development and Pope Innocenzo 2nd gave the abbot the control of all the reformed monasteries on the Lazio borders. During the XII century the Benedictine order had a period of crisis which led to the abandonment of many monasteries. San Rabano was likely to have had this crisis, but the lack of documentation does not allow to know for certain what happened to the Abbey during these particular years. On the 30th of January 1303, Pope Bonifacio 8th ordered Pisa Priorate ( Priorato Pisano) of the Jerusalem Knights ( Cavalieri of Gerusalemme) to vigil, look after, defend, and administrate the lands and the monastery in Alberese ( in the original Italian: “ vigilare, custodire, defender, amministrare le terre e il monastero di Alberese”). In a document dated the 30th of January 1307, the place is still called monastery, while in a successive document of the 18th of October 1336 the word Fort ( Fortilizio) is used for the first time. The fortification, now visible as the raising of the brickworks with battlements, is therefore likely to have occurred at same point between the two dates. Considering that for a short period between 1321 the monastery was under the domain of the Abati Family, tyrants of Grosseto for a few years from 1312, historians tried to find who had started the building work: from an accurate analysis of the construction methods, the fortification seems to be the work of the Knights of Jerusalem ( Gerosolimitani). In the fourteenth century the domain of the fort was cause of disagreements between Sienna ( Siena) and Pisa and in 1438 Sienna, which was now the absolute owner of the area, dismantled the abbey and moved the seat of the Priorato to the new structures of Alberese in 1475. The architectonic complex is composed of a church with a monastery and a sighting tower called of “Uccellina”. For the restoration works there were two main shipyards. Part of the building material was reclaimed and the building itself is likely to have been based on the pre-existing structures, although there is no real evidence of this. The first shipyard can be referred to the end of XI century, while the other to the second half of XII century. The church had a cruciform base with tie beams and vaults in the transepts. The cross-shaped vault of the nave is dated back to the second shipyard, as well as the tower bell and the dome. Particularly interesting is the covering system, partly fallen down, of the central nave, which is considered one of the ancient examples of vaults in Tuscany.
The heavy covering is built in stones and supported by big slabs which lean directly onto the walls of the nave through capitals. Very beautiful was also the “alo tiburio” of the dome which some historians said to be of Byzantine style although made during the Romanic Lombard time. There are also different opinions regarding the exact period and date of the engraves on the arch of the portal and apsidal window: some people believe them to be high-medieval and others of later periods. Stylistic doubts remain also as for the string course of the architrave of the portal. The part facing East is composed by a central apse and two smaller ones at the sides, engraved with suspended arches immediately below the ceiling. The tower-bell string course is definitely Romanic Lombard, but some alterations have certainly occurred above the mullioned windows with two lights, due to the raising of that part of the building, which might have taken place during the fortification of the whole complex. The interiors are particularly suggestive and comprehend a flight of stair, which goes up all along the walls with six flight of stairs leaning onto the arches supported by columns and pillars. Only the first flight of stairs is original, whilst the others have been altered during the restauration work in 1972. The monastery has not been preserved in good conditions and only recent excavations have allowed historians to understand what the whole complex would have been like in the past. It is possible to see the ruins of a central courtyard with cistern, a big driveway and a small one, and an area with furnace near the Uccellina tower, considered the oldest centre in the complex and completely included in the successive brickworks. A few traces in the woods are left of the surrounding inhabited area, along with some cisterns and walls.