The building complex extends along the southern side of Dikaiosynis Avenue. It comprises three distinct buildings and is the result of the conversion of an Ottoman structure dating from the late 19th century.

On this site, in the late sixteenth century, the Venetians constructed the Barracks of St George. Following additions in the seventeenth century, the building reached a length of 261 metres, contained 200 rooms, and featured a large, covered portico along its northern side. After the fall of Candia, the barracks continued in use under Ottoman rule. The Venetian-period building was destroyed by the earthquake of 1856, and on the same site the Ottomans erected new barracks, known as the kışlas. The designs for the new complex were prepared by the architect Athanasios Mousis, and the foundation stone was laid in 1883. The long, two-storey building was covered by a timber roof with clay tiles.

The ornate marble doorway on the building’s northern façade came to be associated with a portal said to have been sent from Rome by Pope Alexander V (1409–1410)—born Pietro Filargo, formerly a monk at the Franciscan monastery of St Anthony at Kares, Mirabello—to be used in the chapel of the monastery church of St Francis. In reality, only the hexagonal pedestals of porphyry marble and the pilaster capitals of grey marble date from the Venetian period and may indeed have originated from the Monastery of St Francis; the remaining elements are contemporary with the construction of the Ottoman building.

After the period of Autonomy and the withdrawal of the Ottoman army, the barracks housed the Heraklion Gymnasium (lower secondary school). In the late 1920s, to designs by the architect Dimitriοs Kyriakòs, the building underwent extensive alterations in order to function as a modern administrative centre. The unified structure was divided into three separate sections, between which broad open-air passages were created. The timber roof and intermediate floors were replaced with reinforced concrete slabs, and the façades were redesigned in accordance with the principles of Classicism.