The first document mentioning the new settlement of Fossa is a papal bull from 1204, which attests to the town's affiliation with the Diocese of Forcona. Another document from 1269 indicates that the municipality participated in the foundation of the emerging city of L'Aquila, although the people of Fossa, probably due to local pride, did not move to or build in the designated area within Civitas Nova. Even today, this space remains empty and is known as Campo di Fossa. In the feudal era and beyond, the town changed ownership among dukes and barons, as evidenced in other documents until 1663.
In a very limited area, centuries of archaeology, art, architecture, myths, and legends unfold, featuring illustrious and saintly figures that have shaped the history and culture of such a small urban center.
The village began to expand beyond its original boundaries from the late 13th century along the ridge of the same karstic sinkhole. The first phase of expansion took the form of a concentric settlement around the fortified enclosure, following the contour lines of the slope, serving as a sedimentation function. The second phase, marked by buildings from the 14th to 16th centuries, has a character of aggregation. The urban layout of the upper part adapts to the local topography, exhibiting features of high medieval villages with narrow winding streets embracing buildings, steep and winding paths, rocky terraces, and stone walls. In the second phase, the central nucleus finds its focal point on the main street of the village, precisely situated above the slope of the mountain. Many residential clusters overlook this street, and all secondary alleys converge onto it.
This second phase indicates a more linear character in the urban layout, in open contrast with the initial phase. Among the prime examples of medieval civil architecture in this second development phase are the 14th-century Casa Torre dei Campione, following the classic multi-story arrangement where the ground floor served as a craft and commerce space, the first floor as a dwelling, and the top floor for defense. The 15th-century Casa Masci presents itself in one of the most suggestive glimpses of the village: simple and elegant, in full respect of Renaissance architectural standards. Notable artistic achievements include stone portals on several 16th-century palaces adorned with the typical Franciscan emblem depicting the symbol of San Bernardino da Siena, namely the sun carrying the monogram IHS: JESUS HOMINUM SALVATOR. Various noble palaces (Bonanni, Lazzaro) continued from the late 16th century to the late 19th century, attesting to the enduring economic prosperity of the small village.
