After the year 1000 the Normans Drengot, become beneficiaries of the fief, transformed the city and the rudimentary Lombard tower in fortellicium, i.e. fortress, composed of a real castle of tufa built near the south gate and a system for strengthening the kastron by buttresses and sighting towers; Roberto Drengot, Count of Alife, Caiazzo, Airola and Sant'Agata de' Goti, settled in the castle his dwelling place in front of the chapel of counts, at the foot of which we can still see today the quarry of the factory said "pit".
The quadrangular towers Norman today is still perceive: The Castle keeps track of high medieval environments on the ground floor, while on the outside it is evident the projecting body added in the nineteenth century with a series of workshops. In the courtyard you can admire even the beautiful mural decorations with geometrical motifs fifteenth, and changes of the xvith century, made to transform the fortress into a noble residence of prestige: in fact it seems that in Angevin period there were hosted for some time Giovanna I, Queen of Naples and Provence, protectress of the feudatories "Artus" race cadets, coming from the land. After 1400, extinguished the Artus, the castle was inhabited alternately from the De la Rath, by Cossa, and by Acquaviva. In the Sixteenth Century, in order to strengthen the defense toward the east, was realized a new circular tower used as a prison until modern times. The surface on which extends the castle is equal to more than 3000 square meters: near the south door, today piazza Tiziano Della Ratta, had to be the space reserved for the equestrian training and preparation of the soldiers.
In 1696 the Carafa family Della Stadera of Maddaloni bought the castle already very altered as a prize of the king for the fidelity and loyalty demonstrated in time: the Carafa, Neapolitan family born in the 14th century, divided into various seeds on the basis of activity and fortune, was in fact assigned by centuries the task to protect and control the most important hubs roads of today's Campania. Was Domenico Marzio Carafa duke of Maddaloni, died in 1703, to acquire the castle of Sant'Agata at the end of the Seventeenth Century; he did not have much time to abitarlo: moreover the Carafa di Maddaloni possessed many dwelling places scattered in the land of Work Not all inhabited and habitable. They, once acquired were assigned to various members of the family as an inheritance, so that each started a new cell for its own account.
The castle of Sant'Agata was assigned to the daughter of Domenico Marzio, the duchess Caterina Carafa della Stadera of Maddaloni married with Domenico Carafa prince of Colubrano, early twenties: the couple decided to dwell at the feud since some of the halls of the castle bear witness to a renewal that never would have happened in a dwelling not inhabited. Are part of the decorations the frescoes to images so-called "grotesque" of the hall on the first floor where the painter Tommaso Giaquinto realized at the beginning of the Eighteenth Century a scene depicting Diana and Actaeon.