After the Roman era, area occupancy was quite superficial. The Legion XIII Gemina left the province, leaving behind a few veterans who decided to stay here. Civilization no longer has the same pace of growth, and waves of barbarians made it extremely difficult to build sustainably and consistently.

When civilization stagnates, like in this case, we receive little information to decipher and understand the life and behaviors of people from those times (4th-10th centuries). For the post-Roman period, some traces of habitation (houses dug into the ground) and organization have been discovered, including on the plateau of the former legionary camp. Roman fortifications continued to ensure the defense of the inhabitants, complemented by new ones. The Slavic toponym of “Bălgrad” (White Citadel) originates from the 9-10^th century, probably inspired by the white walls of the former Roman fort.

Later, a gap spans several years until the period of the settlement of the Hungarians (10th century) and the formation of the Hungarian kingdom under the Árpád dynasty (1000-1301). Over time, dwellings appear in the southwest corner of the former Roman camp, part of the ensemble of the first episcopal residence in the citadel. The first Roman Catholic Cathedral was erected (11th-12th centuries).

The place gradually takes on the image of a fortress with varied interior structures, indicating, however, a precarious urban evolution. After the 12th century, the city began to take on the air of a medieval one, especially after becoming an episcopal seat with recognition. Officials join the high prelates, all in the service of the bishop. The fate of the city and the future The Princes` Palace is linked to the new construction of the Roman Catholic Cathedral (13th century) and the building of the first structure (end of the 13th century) attached to the new Episcopal Palace. It is called the “Gothic body,” incorporating the old bell tower from the first Episcopal Palace, now identifiable in the overall part where the Roman Catholic Archdiocese of Alba Iulia operates today.

Between 1460-1470, parallel to the Episcopal Palace, another medieval structure with specific functions for clerical life rose to the east, occupied by the leader of these high prelates, called the prepositus (Preposit’s Palace).

From this moment until the penetration of the humanistic spirit of the Renaissance into Transylvania, along with its art and philosophy, no traces of constructions have been recorded that provide a relevant archaeological context.

However, everything changed with the arrival in Alba Iulia of a person who decisively marked the history of the Principality of Transylvania. Her name was Isabella Jagiello, the queen consort of Hungary, expelled from her seat in Buda by the Ottoman Sultan.