During the siege of Bari in 1071, Robert Guiscard had a stone guard tower built to protect the ancient port. However, the tower already started to show signs of structural failure around 1359. Its potential collapse threatened the church underneath, which was probably dedicated to San Nicola by-the-port and is referred to in a number of historical documents from 1178 and 1226. It is from this church, as well as that of the Saint Antonio Abate chapel, that remains incorporated within the fort walls were discovered during numerous restoration programmes.
In 1440, after a series of reinforcements, Caldora, a local feudal lord, built a tower in the same spot which had “the guise of a small castle”. As with all “forceful” signs of power, the locals did not welcome this development and around thirty years later, they razed it to the ground.
During her campaign of restoration and beautification of the old town between 1501 and 1524, Isabella of Aragon oversaw the rebuilding of the tower and the renovation of its original appearance. It was inserted into the quay, which had already been embellished by a Roman column acquired from the church of San Gregorio de Falconibus. Today, this column is situated with other examples at the foot of the first section of wall by Piazza Ferrarese.
Additional restoration activity was carried out by the Bari Universitas from 1548, resulting in its fortified appearance similar to today’s (a work spanning 1560 to 1578).
Following further work during the reign of Charles III of Bourbon, the tower was taken over by the mayor of Bari but later fell into disuse.
It was not until the period 1994-2000 that the local council (owners of the building) and the Cultural Authority implemented a campaign of restoration under the direction of the architect Cusatelli in order to give the edifice back its dignity and value and to return it to the local population for different functions.