The first documentary sources related to the settling on Grottammare’s hill, date back to XI century, but its origin is certainly previous and deals with the appropriation of the St. Martino’s curtes by the Farfa’s monks who had jurisdiction over these lands and had fortified this area in order to defend the population both from the numerous invasions and wars.
The architectonical structure’s analysis emerges from the wall ornaments dating back to XII and XIII, which might be attributed to the restoration undertaken by Fermo after having obtained Grottammare. Other wall structures might be dated around XV and XVI and testify the several restoration works done on the castle after the first foundation.
According to ancient descriptions, the castle was completed by a tower which did service as a lighthouse and which was situated on the highest point of the fortress. The ancient Historians as well as the iconographical sources of XVII andXVIII describe the tower-lighthouse of cylindrical shape, developed on three floors and probably provided with an entrance door to the castle. In 1766 it was partly brought down since it was unstable and in the first decades of XIX century disappeared the remaining part owing to demolition and landslides.