Porta Mesagne is the oldest gateway to the city. It was built as early as 1236 by the will of Frederick II of Swabia. The hinges on the heavy doors are still visible in the pointed arch.
On the large pentagonal bastion, set in the Aragonese period and renovated during the viceregno, are the coats of arms of Emperor Charles V, the viceroy of Naples Don Pietro da Toledo and the military engineer Giovan Battista Loffredo. The second smaller opening, next to the door, was opened around 1930. Adjacent to the bastion are still visible the remains of the limarie tanks (parts of the aqueduct used for the decantation of the water) dating back to Roman times whose vaults were demolished for the construction of the defensive system.