Porta Aquileia, once also called Porta Marittima, as it faced the Adriatic, was the first of the three gates of Palmanova to be erected in 1598. The external construction is clad in Istrian stone and stands out from the others for its greater elegance as, at the time of the Serenissima Republic, it served as the representative entrance for illustrious guests and the General Superintendents. 

The facade of Porta Aquileia, in fact, is embellished by two large volutes that embrace the guardhouse. Also pleasing to the eye are the refined friezes and baroque elements that decorate it. 

Under the guardhouse, on the cornice, rested a large stone lion of St. Mark, later chiseled by the French in 1797. 

Like the other two gates, it was defended by a drawbridge, gates, and imposing equipped doors: every evening it was raised, making the fortress impregnable.