Designed by the architect Giovanni Maria Falconetto, the gateway was completed in 1528, during the reign of doge Andrea Gritti. The main facades – some 14 metres wide – are organised according to the classic schema of a tripartite triumphal arch and are almost entirely faced with trachyte. The one exception is the parapet; this also has two embrasures on either side, which are a clear indication that the gateway still had a military function. To the sides of the central arch are two symmetrical gateways framed by pilaster strips and surmounted by pediments; these appear to be intended for pedestrian use, but only the one to the south side of the structure was an actual gate. During the Napoleonic period the gateway lost the frieze of the Lion of St. Mark which had once surmounted it. Within the gateway, the Contarini crest is repeated on the right side (as you enter from outside the city), and the crest on the left is that of Maffeo Michiel, who was podestà in 1527.
The interior space is square in floor plan, and has projecting corner pilasters and a rib-vault ceiling. From a door in the middle of the external south side of the gate, you can take stairs that run up within the walls to the room directly beneath the roof. To the south of the gate, within the city walls, was located a casemate for the artillery which covered northern side of the Bastion of San Giovanni. The eighteenth-century bridge on the outer side of the gateway ran over the moat, which was wider and deeper than the space one sees nowadays (it has been eaten into by the needs of modern road traffic). By the gateway runs a narrow canal called the Fossa Bastioni [Bastion Moat], which follows the course of the city walls.