The first cathedral has been built in the 11th century during the reign of Saint Stephen, the first king of Hungary.

The diggings that have been undertaken since 1907 and especially the one which began in 1967 (the former was led by István Möller, the latter by Lajos Bágyuj) clarified that the first cathedral was built in the time of Saint Stephen. It was a church in the style of three-nave ancient Christian basilicas. The width of the main nave was 8 m, that of the aisles 3,5 m.

The main nave ended in a wide, semicircular apse, the aisles show a straight ending at least in the outer walls. During the first excavations, were found the basement of a ring-shaped chapel and the southern walls of it. During the second digging were found the western basement walls too. From this cathedral were saved carvings showing human heads that were in the southern wall of the main nave, fragments of the flatly carved rim and pillars and a relief from the ridge of roof, which was placed later into the interior part of the southern gate.

Recent diggings clarified the question of the ring-shaped chapel too, which has been known for a long time. It became clear that the basement walls of the ring-shaped chapel are similar to the other basic walls and wall system of the cathedral. There is no evidence that the chapel would be the result of two different buildings. It was the baptising chapel of the first cathedral, very much like the Saint Stephen chapel at Székesfehérvár.

This first chapel might have been destroyed in the revolt of Vata (1046), or maybe the rapid development of the diocese required the building of a larger cathedral.

Around the first cathedral a cemetery was revealed in which relics referring to the 12th century were found, among others, coins from the time of king Stephen II. (1101-31) and king Stephen IV. (1133-65).

The second Cathedral

It is thought that its building was done in the 12th century but they began to build it during the reign of king Saint Ladislav about whom Pelbart of Temesvár said that he supported the building of the cathedral.

The second cathedral is much larger than the first one, so they couldn't have used the latter's basement. The former basement remained within the walls of the church. This too had three naves, a transept and a central tower. It represented the semicircular Romanesque style and the churches from Burgundy, France and Alsace served as examples to its building.

The main sanctuary ended in a simple semicircle behind the rectangle. It is thought to have had a flat ceiling. It had two towers on the facade and one at the rectangle, the former ones reached only the third floor at the beginning.

In this period the triumphal arch were built, the arches of the transepts, the semicircular endings of the lateral sanctuaries, the rectangular sanctuary and the narrow windows of the side apses

The sacristy, the eastern sequel of the vault of the long naval, the northern porch and the princely gate were built later, but before the Mongol iinvasion of Hungary in 1240-42.

On this occasion the Mongols set fire to the church, the vault collapsed just like the domed middle-tower built above the crossing of the navels. Rogerius, the canon of Várad (Oradea), describes it as a ruin the walls of which were blood-stained and the corpses and skulls scattered around it offered a horrible sight. Yet the church was rebuilt. To the rectangle of the sanctuary a new, slim sanctuary was added in an early Gothic style, they reset the first rectangle of the transept, the four pilasters above which, under the woodwork of the roof we can see the remainders of the middle tower, which was not rebuilt.

The vaults of the western part of the main naval were built only in the next century, its age is shown by the coat of arms of bishop András Széchy that is to be found on the headstone of the second sequel. By that time the southern tower was also heightened by three more floors. Two more floors were added to it as late as in the 15th century.

No sooner had they finished the renovation than they had to do it again. On 21st February the Saxons living around Vízakna (Ocna Sibiului) plundered the church again.
In order to make the rebuilding of the church possible Ladislav IV donated the salt-mine from Torda (Turda) to the chapter of the cathedral and ban Mykud gave up his plans of undertaking a pilgrimage to the Holy Land and offered his estate of Szentmiklós, near the town of Torda (Turda) so that the church of Archangel Saint Michael should be rebuilt.

The earliest fresco is from the middle of the 14th century; it is a flowery foliated scroll on the southern rim.

In 1439 the Turkish army plundered the southern part of Transylvania and the cathedral must have suffered again because György Pálóczi, the archbishop of Esztergom sent 1000 guldens to György Lépes to repair it and in 1440 and 1442 János Hunyadi made a mass-foundation by donating Bolgárcserged, Diómál and Tinód to the cathedral at the same time expressing his will that his brother and later on he himself be buried in the cathedral.

According to some experts the lengthening of the sanctuary in a beautiful Gothic style was also done of Hunyadi's donation, but others think that it was built after the Saxon devastation.

In the first decade of the 16th century canon János Lászay turned the northern porch into a chapel in which an altar named Fidelium animarum (faithful souls) was placed. The altar was finished in 1512, Gothic and Renaissance elements are blending in it and it has a series of reliefs: Our Lady, in front of her is kneeling Lászay himself, mythological figures, figures from the Bible, saints (Judith, Samson, Moses, Hercules, a Centaur, Saint Sebastian, kings and two knights).

Between the years 1514-1524 bishop Ferenc Várday had a new chapel built between the Lászay chapel and the northern transept which was dedicated to Saint Anne.
By this time the fresco of the northern side nave had been painted. It has two levels; on the lower one there are Saint Andrew and Saint Antony the Hermit, on the upper one Saint Thaddeus.

János Hunyadi built the adorned western main gate in a pointed arch style; he had a beautiful balcony raised between the two towers. Later, in the time of bishop Sorger, this balcony was confined by a tympanum and four statues were placed on it.

The western tower was blown up during the siege of 1603 and has never been built up again.

The church continued to have a troubled history. In 1601 it was plundered by mercenary troops, which did not spare Hunyadi's grave either. Two years later it was literally besieged and invaded by the soldiers of Basta. In 1658 and 1661 the sultan wanted to punish Transylvania and sent an army against it. The Turkish soldiers destroyed the church, ruined the beautiful tombs of Gábor Bethlen and György Rákóczi I. Bishop Mártonfy had an adorned altar built at the beginning of the XVIII century from the material of the latter.

The cathedral used to be a real pantheon of the important historical personages who were buried there. Besides those whom we mentioned: László Hunyadi, János Hunyadi, János Zsigmond, Queen Isabelle, István Bocskai, his wife Zsuzsanna Károlyi, István, the brother of Gábor Bethlen, György Fráter Martinuzzi, Endre Báthori and several bishops of the Middle Ages. Ten bishops of the modern age, the last of them being Áron Márton, were also buried here in the crypt under the sanctuary.