The most imposing symbol of Venetian presence in Candia, and the largest fortification project undertaken by Venice in the Mediterranean, is the large-scale fortification of the 16th century, which survives almost intact, encircling the old town. The growing Ottoman threat led to the design of a new defensive perimeter, adapted to the use of heavy artillery and based on the principles of the bastioned system (Fronte Bastionato).

The implementation of this ambitious programme, whose planning began in 1462, encountered numerous difficulties, engaged successive generations of engineers, underwent repeated modifications, and was effectively completed only with the fall of Candia in 1669. A decisive contribution was made by the Veronese architect Michele Sanmicheli (1538–1539), while the final form of the enceinte was shaped by Giulio Savorgnan, Provveditore alle Fortezze and later Provveditore Generale (1562–1566).

The fortress follows a strictly geometric design, with a polygonal plan and seven heart-shaped bastions: two maritime bastions (Sabbionara, or the Bastion of the Sand, and St Andrew) and five land bastions (Vitturi, Jesus, Martinengo, Bethlehem and Pantokrator). The bastions are connected to the curtain walls by necks (gole), where platforms for heavy artillery were laid out. The moat was created through the excavation of the earth required for the construction of the fortifications, which encircled the city as a continuous embankment. The outer face of this earthen mass was retained by a sloping stone revetment (scarpa), above which rose a vertical parapet (parapetto), articulated by a semi-circular moulding (cordone).

The narrow dry moat, detached forts and ravelins reinforced the defensive system by restricting the deployment of attacking forces. Despite the intense bombardments of the twenty-year siege, the fortifications have survived almost intact, standing as a lasting symbol of human ingenuity, resilience, defiance, and the unyielding quest for freedom.