Built on the site of an older and smaller cathedral, the new church, whose patron is Saint Michael, was the most imposing ecclesiastic building in Transylvania before the construction of the great churches in the main Saxon towns in the fourteenth and fifteenth centuries. Construction began possibly during the early thirteenth century, when the apse and choir were erected. The old church was still standing, being demolished gradually as new parts of the new church were constructed, so that the liturgical services could be continued for the bishopric and the people. The Mongol invasion of 1241-42 disrupted the work, but construction was resumed after the appointment of Bishop Gallus in 1247. Around 1260, the model of a five nave building was adopted, thus the number of collateral naves doubled in the area of transept. But soon afterwards this plan was abandoned and the old plan was readopted. Construction was again interrupted in 1277 and the unfinished cathedral suffered damage when the Saxons attacked the Bishopric of Alba Iulia.

The construction work continued for decades, starting in the Romanesque period, adopting architectural and decorative options specific to early Gothic, and ending in the 1290s under the control of master mason John of Saint-Dié, when the southwestern tower and the portal on western façade were erected.

The church was built with stone blocks taken from the walls of the Roman fortress. It has the plan of a Romanesque basilica, with three naves and two towers on the western side, along the collateral naves, and one tower above the square. On the eastern side of the naves, there are quadrangular spaces, oriented transversally, which together form the transept, which was reserved for the numerous clergy of the bishopric. They also used the quadrangular, choir located between the apse and the transept. The semi-circular apse sheltered the main altar of the church, while the small apses located on the eastern sides of the transept hosted two secondary altars.

The cathedral was adorned with beautiful and abundant sculptured decoration, noticeable on the eastern side on the small apses and at the southern side on the portal elements, especially on the jamb columns covered with stone lacing. An outstanding sculpture appearing on the tympanum of the portal depicts the scene known as Maiestas Domini, an alto-relievo representing Jesus Christ seconded by apostles John and Peter. Another alto-relievo with the same iconographical theme, but dating from the twelfth century and belonging to a portal of the former cathedral, was mounted on the same portal inside the cathedral. Inside the cathedral there are decorations mostly on the capitals which support the rib vaults of the naves.

An important reconstruction of part of the church was undertaken in the first half of the fourteenth century, during the office of Bishop Andrew Szécsi (1320-1356). A new Gothic choir with a hexagonal apse replaced the former one. This new choir, in contrast to the rest of the building, had large windows corresponding to the features of the new architectural trend in Europe. This was the earliest Gothic monument in Transylvania.

In the fifteenth century the towers were heightened. In the thirteenth century they had been constructed up to the cornice. In 1603, the northwest tower was destroyed by the explosion of gunpowder which had been deposited within it and was never reconstructed.

The monument received another remarkable addition in the Renaissance period. In 1512, John Lázó, archdeacon of Tileagd, founded and donated a chapel dedicated to the Holy Spirit. Placed on the northern side, the chapel represents the most important early Renaissance monument in Transylvania. Its composition includes architectural elements specific to the new style, which was slowly penetrating this part of Europe, mixed with Gothic elements. A couple of years later, during the office of Francis Várday (1513-1524) other additions and decorative works were carried out. Next to Lázó’s chapel, on the east, in the space of the two northern collaterals, a chapel dedicated to St. Anne was built. Nowadays only the northern façade is preserved.

After the advent of the Reformation and its rapid adoption in Transylvania, the Roman Catholic bishopric was abolished in 1556 and Calvinist Protestants used the cathedral. During this time, the church was deprived of its painted decoration, as the Reformed confessions did not agree with these representations in church. Traces of frescoes dating from the fourteenth and sixteenth centuries were discovered in the embrasure of a window in the northern branch of the transept and the small apse near it. The altars of the church and certain furnishings, such as an organ mentioned in 1520, were destroyed shortly after the Calvinists took over the cathedral.

In 1716, the cathedral was returned to the Roman Catholic Church and new restoration and beautification works were carried out, such as in 1728, when four statues depicting King Stephen and King Ladislas of Hungary and the bishops Adalbert and Gerard were mounted on the fronton located between the towers on the western side. A new sacristy was built at the same time on the location of the medieval one. The most remarkable intervention was the complete reconstruction of the Gothic apse, which was crumbling by the mid-eighteenth century. The church received new furniture, such as the pews of the canons in 1744. The main altar was built by Simon Hoffmayer in 1783-84, after a command sent by Ignatius Batthyány.

Apart from the altars and furniture of the eighteenth century, the cathedral displays numerous funerary monuments, such as those of the Hunyadi family members (John Hunyadi, his brother John Jr. and his elder son, Ladislas). Nowadays, these monuments are located along the southern collateral nave near the portal, although it seems that initially they were located in the transept. Other funerary monuments are located in St. Anne’s chapel, such as the sarcophagi of Queen Isabella Jagiellon and her son Prince John Sigismund, the epitaphs of Bishop George Martinuzzi and those of the main architects of the Vauban fortress, Giovanni Morando Visconti and Francisco Brilli.

In spite of many transformations over time, the cathedral maintains a unified appearance, with the diverse architectural elements specific to the successive styles which appeared during its lengthy existence integrated harmoniously in its structure. The edifice has impressive dimensions – length 81.35m, breadth 32.85m, height of central nave 19m, height of tower 55.5m – making it one of the most important monuments from this part of Europe. (C.A.)