Introduzione

The study conducted on the masonry of the Castello di Lombardia and the historic center of the city of Enna provided numerous data regarding the various phases that affected the site. As for the Castello di Lombardia, the different phases that affected the entire architectural complex were identified, initially considered to date back to the Swabian period. The research highlighted an initial occupation of the site during the classical and late antiquity periods. This is followed by the Byzantine fortification, built at the highest point of the Enna acropolis, coinciding with the San Martino courtyard. Four pseudo-square towers, connected by several curtain walls, can be identified. The other two courtyards of the castle have yielded faint traces of the Byzantine layout, which do not allow for an adequate chronological sequence compared to the other architectural evidence. On this structure, the Arab-Norman, Swabian, and modern phases were organized. The study of the masonry in the historic center allowed the identification of earlier masonry structures incorporated and/or reused in modern-con- temporary buildings. A total of 118 masonry walls were identified, which allowed the distinction of five different types of masonry. Most of these are structures in squared stone, divided into several variants that highlight the evolution of the technique itself. Of particular interest is the USM 10087, identified within the municipal cemetery; this is a section of masonry that belongs, from a typological point of view to Romanesque architecture, and it is located at the site where the historical maps show the Torre di Federico.