Surveys carried out between 2016-2019 in the territory of the Maremma Park led to the discovery of a medieval settlement, apparently previously unknown. Lying within a small valley among the Uccellina hills, it is situated immediately south of the castle of _Collecchium_ (in the territory of Magliano in Toscana - GR). At the site, part of a church built in Romanesque style (11th – 12th century) and associated buildings (the foundations and a few other remains) are visible; at the time of the discovery, they were largely hidden by collapsed material. The data collected during the surface surveys documents occupation between the late 11th and the 13th centuries, a period in which the interests of the Abbey of San Salvatore al Monte Amianta were intertwined with those of the powerful Aldobrandeschi family. The site can be added to the few remains from this period that have been documented south of the castle of _Collecchium_. Its study may offer new data of use in understanding the settlement dynamics of the territory in the period preceding Siena’s acquisition of the nearby port of Talamone in 1303. In 2019, a project was undertaken to record and enhance the site, which has now become part of the visitor’s itinerary within the park.