This essay enlights the leading military role played by the city and harbour of Ancona in the Marches, against Muslims attacks, during the XVI century. Antonio da Sangallo jr. designed the strong "Cittadella" above the Astagno hill and other famous military architects carried on the huge "Campo Trincerato" around it, such as Pier Francesco da Viterbo, Giovan Battista Pelori, Pellegrino Tibaldi, Francesco Paciotto, Giacomo Fontana, etc. Born in Ancona, Fontana wrote (1588) a report for pope Sisto V on conditions of the fortifications of his mother town, with several drawings (Codex Vaticano Latino n.13325), which is interely published and widely explicated here, for the first time, by Mariano.