Acronafplia (Turkish Ichs-Kale) is a rocky peninsula that used to be the acropolis of Nafplio in antiquity. It is opposite Bourtzi and to the right of Nafplio at the entrance to the Argolikos Gulf. It is only accessible from the North by an artificial historical ravine called Arvanitia. This peninsula has an average height of 45 m above sea level, a maximum length of 900 m east to west and a width of about 400 m. today.
The story of Akronafplia traces the historical fate of Nafplio to the Romans, the Byzantines, the Franks, the Venetians and the Turks of the Ottoman Empire, until the liberation of Greece. In particular, the Venetians had systematically reintroduced the fortification in accordance with the new fortification regime imposed by the discovery of gunpowder and the simultaneous use of firearms. Thus in 1502 they increased the fortification by constructing the northeast tower facing Palamidi as well as the autonomous bastion on the west side towards the bay, where they were mounted five large cannons (cannons), the so-called five brothers and five brothers. the then-name castle of five brothers.
In 1540 Nafplio was occupied by the Turks who further strengthened the fortification of Akronafplia with larger canons naming Its-Kale (= inner castle). In 1686 it was followed by the second Venetian domination of Nafplio and that in 1715 by the second Turkish domination. During this period the Turks strengthened It-Kale and Palamidi by 400 cannons, 84 of which were 64 pounds each. On the eve of the Greek Revolution of 1821 the Turks continued the repairs and new construction of the castle.
On the night of November 30, 1822 the Greeks under Staikos Staikopoulos occupied Palamidi and with its canons began to regulate Akronafplia. On December 3 (just 3 days later) the Turks were forced and handed over the castle to then-Major General Theodoros Kolokotronis who hoists the flag of freedom at the battlefields and places Spetsiotis Anastasios Koutroubis as the first guard in the castle. Unfortunately, however, the Greek fugitive that broke out in 1824, which resulted in the capture of Kolokotronis and his imprisonment in Hydra, led the then government to change its guard by placing its trusted Nassos Photomaras. In 1828, when Ioannis Kapodistrias became the commander-in-chief of the Fortresses of Nafplio, he was taken over by Colonel Carl Wilhelm von Heideck who in turn assigned the Akronafplia Guard to 50 Spetsiou N under Spetsiotis.
At that time the Governor, realizing the value of the fortress, made sure that it was cleansed of the piles of rubble and rebuilt all the damaged sections as well as the completely demolished rampart. He also built a military hospital on the site as well as a small temple near it.
During the reign of Otto the Bavarian army that took over the Nafplio Guards completed the fortifications, the construction of military warehouses and the refinishing of the military hospital. After moving the capital from Nafplio to Athens, Otto ordered in July 1835 the general repair of all the Acronafplia fortifications and bastions, as well as the provision of new firearms.
During the reign of George I, large infantry barracks, military prisons, and large underground rainwater storage tanks were built inside the fortress. At that time Akronafplia was the center of all the troops of the Peloponnese.
Under the reign of Constantine I and Alexander I, the military prisons of Akronafplia began to gradually become more accustomed to the newer penitentiary systems and the employment of convicts in professional activities, setting up various garages, eg. carpenters, shoemakers, etc.