The objective of this research is regarding the construction techniques used in the military architecture of Cittadella-Fortezza (Ancona, Marche, Italy). In this case, attention will focus primarily on historical, bibliographic and archive research, then through a comprehensive analysis of building methods used in the sixteenth century and on the strategic function that this fortification covered in the coastal strip of the Middle Adriatic. Together with Rocca Paolina (Perugia) and Fortezza da Basso (Florence), it has in fact a remarkable importance in the military architecture’s history, as it was one of the first experiments of fronte bastionato all’italiana. Built from 1532 by Antonio da Sangallo il Giovane, it rises on the top of Astagno hill in a panoramic and defensive position, overlooking the city and the port. It clearly distinguishes itself from the surrounding building fabric as it is characterized by five mighty bastions in bricks and by the central bulwark with the vaulted ground floor. The study aims to investigate the structural details of Ancona’s fortress such as the modeling of walls, the suppression of protruding volumes, the extension and rounding of the corner towers and the introduction of the central type plan. A great understanding of this research will be analyzed in the drawings and the volumes’ reliefs, which highlighted the general geometric data, the materials used for the realization of the work, the angle of the curtain walls and the technical/constructive strategies. Therefore, the methodical-metric knowledge of the parts will be made more accessible also in relation to the three-dimensional modeling of the fortress, in addition to the critical comparison based on other historical examples of military architecture in the Renaissance period.