The whole building was occupied by prisons, except the upper loft. Prisoners used to gather frequently in chains in the big vaulted common rooms. There were cells reserved for special convicts on the floors by the steep ladder.
Until the first decades of the nineteenth century, the prisons located in the Tower were destined to hold political prisoners, people who were accused of heinous crimes, and, in the more comfortable upper cells, leading members of aristocratic families waited to be ransomed.
Common prisoners used to be put into the cells next to the Palazzetto Criminale (now the seat of the Archivio di Stato), which was connected to the Palazzo Ducale by means of a suspended pontino (aerial bridge).
By looking at the records of the trial against a prison guard named Giovanni Battista Noceto, who was guilty of illegally helping some prisoners, we come to know the funny names given to the cells: Paradise, Pride, Little Queen, Women, Moon, Palm Tree, Hen, Witch, Fox, Hospital, etc. It seems that there was also a cell called Grimaldina, from which the Tower took its name.
The so-called Grimaldina prison, usually reserved for political prisoners, was located in the old Palazzo del Comune, west of the tower overlooking Via Tommaso Reggio. It is easy to figure out what life was like up there: scarce food and cold weather undermined the prisoners’ health.
For a long time prisoners were supported by the charitable actions of common people. Convicts used to rest on fetid straw mattresses, wrapped in dirty blankets. In winter, they often tried to shelter from the sleet and the wind, which blew through the grating, by piling their straw mattresses and blankets up against the windows.