The Polveriera Veneta is a cylindrical-shaped construction from the end of the 15th and the beginning of the 16th century, made of stone blocks and with a diameter of about 7 meters. Originally covered by a brick vault, it was used to store gunpowder and ammunition for the defenders of the fortress and was probably connected, through underground paths, with the defence buildings on the Colisello and some of the towers.

The building, recently restored, is of considerable importance as there are no other examples of a circular gunpowder magazine in the Friuli Venezia Giulia region.