The history of the castle follows step by step the history of the city at least from the 6th century AD onwards.
In the Greek era, and then following in the Roman period, the hilltop postion of the castle would certainly have had a fundamental importance to the protection of the city.
During the 6th century, perhaps ahead of the invasion of Totila (549-552 AD) it was decided to fortify the area but it was not until the byzantine era, between the 9th and 11th century (when Reggio became the capital of the “Thema di Calabria”), that a real castle was built on the hill. That said however the increased fortifications were probably more for byzantine defence and most probably only a tower was constructed.
In 1039 the city passed over to the domination of the Normans under Roberto il Guiscardo and in this period a fort was built, in other words a tower-fortress which rested on the city walls and was destined for the troops who would defend the city.
The actual building of a castle, instead, was revealed at the moment of the construction of the original structure (visible from photos and remains from the structure following the 1908 earthquake) which show military construction of that period. An imposing, square form building, with 60m long sides and four angular towers, also square in form. According to some scholars, however, it is thought that the fortress may have taken this form in the course of the 12th century.
During the 13th century the castle underwent certain transformations.
During the repeated wars between the Anjou and the Aragons it was restored in 1327 and fortified in 1381 by Queen Giovanna I. A document from 1382 speaks of six towers along the perimeter of the castle.
After the Aragons conquered Reggio in 1440 also the castle was fortified further under the orders of Ferdinando d’Aragona who wanted to increase fortifications throughout the “Regno di Napoli” against aggressors using new military techniques and gun powder. Therefore, following this work of increased fortification, which lasted 15 years, two further circular towers with parapets were added (which are today the only remaining evidence of the ancient splendor of the fortress) and a pit all around the structure. Initially, the parapets (which were heightened during the 1600s) were slower, and therefore nearer the lower arched band. After every three arches there was an opening to allow rocks to be thrown onto attackers; the lowered slope ensured the stones would rebound while the cornices with rounded edges prevented enemies to access the upper level. On the eastern side of the structure a separate structure was added, that is another towered structure which served to defend the main structure more effectively from armed attack, and primarily from arms positioned on nearby hills and launched at a distance. It also served to house artillery.
During the 16th and 17th centuries, work was started and undertook to repair damage incurred overall following the continued attacks by the Saracens.
In 1539 Pietro da Toledo, vice of Francesco I, increased the internal capacity of the castle, so much that almost a thousand citizens were able to find shelter in the castle and were eventually taken prisoner along with the governor, when in 1543, the castle was taken by the Turks of Barbarossa.
Towards the end of the 1500, it was decided to increase the height of the towers to render the castle safer and make it easier for the coastal towers and the castle to communicate.
In 1712 the castle passed under the rule of Carlo III of Bourbon who, reorganized the internal structure to house military barracks and liberated the pit around it which was often occupied by illegal constructions. The progressive consolidation of power of the Bourbons throughout southern Italy made the requirement for further restoration work less urgent and therefore the need for Reggio to be fortified and particularly the castle became useless.
Following the earthquake of 1783 the castle was converted into a prison and was used for that purpose for many years.
Still after the uprising of the 2nd of September 1847 and the killing of general Pinelli, governor of the city, in the underground tunnels around the castle prisoners were still kept.
On the 21st of August 1860 the Garabaldini took the castle. In the years following the unification of Italy, in 1874, the council bought the castle with the intention to demolish it and build in its place a large public square. After great protest, it was decided to maintain the two remaining towers, but the demolition of the rest did not take place due to long bureaucratic reasons.
Following the terrible earthquake of 1908, which caused serious damage to the structure, the Civil engineers classified the structure as inaccessible. It was decided, within the new building plan for the city, to demolish it, allowing therefore for the extension of via Aschenez ad therefore only the two circular towers were to be left standing.
The demolition was undertaken in 1922.
Today, following the most recent restorations made in 2000, the castle is used for temporary exhibitions and cultural events.