In the 16th century, Alba Iulia witnessed an extremely interesting phenomenon that changed Western culture from art to philosophy and religion. This phenomenon is the Renaissance, with its simple yet harmonious and elegant forms. It brought back the ideas and knowledge of antiquity, interpreted from a Christian, humanistic perspective.

Education and learning, actively supported by the Church and its high-ranking clergy, became the vehicle that introduced this new spirit to Transylvania. Therefore, it was no surprise that, after 1520, a bishop, Ferenc Várdai, and a prepositus, Ferenc Szeremlyéni, transformed the palace in the spirit of Renaissance architecture—modified facades, a new window frame marked with the bishop’s coat of arms, and prominent decorative plaster reliefs at the bottom of the facades called “bossage”.

In 1542, with the death of the last medieval Roman Catholic bishop John Statileo,  the Transylvanian Diet designated the Bishop’s Palace as the residence of Isabella, dowager Queen of Hungary and her infant son, John Sigismund. The two had to leave Buda for Transylvania on the Sultan’s order and settled in Alba Iulia. From the queen’s residence, it later transformed into the Princes` Palace for over 150 years. The queen appreciated Renaissance architecture and incorporated it into the expansion works of the palace, inspired by the residences where she had spent part of her life—Wawel Castle in Krakow and the Royal Palace in Buda. The palace extended to the west, reaching the wall of the old Roman fortress.

Successive interventions followed that expanded the palace ensemble in all cardinal points, but also dramatic events that led to its ruin (1600-1603). One prince, one change. John Sigismund (1559-1571), Isabella’s son, focused on the first courtyard of the ensemble, enclosing it to the south and east. Then came disaster and the ruin of the palace.

In the late Renaissance period, which coincided with the era of the most important Transylvanian princely families—Bathory, Bethlen, and Rákóczi—the surface of the palace significantly increased with its new status. During the reigns of Princes Sigismund Báthory (with interruptions between 1586-1602) and Gabriel Bethlen (1613–1629), the palace rose from the ashes and expanded to the north and south, reaching the Gothic (medieval) section from the west of the ensemble, where the former Episcopal residence was located.

In line with the principle of “one prince, one change,” during the reign of Gheorghe Rákóczi I (1630-1648), the Diet Hall and the Tabla, the supreme judicial forum of the Principality, emerged in the building that now houses the museum. The concept was initiated by Gabriel Bethlen.