The Cathedral Basilica of Saint Stephen was built in the late 1010s by Saint Stephen I, the first King of Hungary. It was the most significant place of the Kingdom of Hungary in the Middle Ages, as it contained the crown jewels, including the throne, the Holy Crown of Hungary, the treasury and the archives. 37 kings and 39 queens consort were crowned in this basilica and 15 were buried in it. In 1543, the Turks occupied Székesfehérvár. The royal graves were ransacked and the basilica was used to store gunpowder while St. Martin's Cathedral in Pozsony became the new coronation site.
In 1601, the valuable building was destroyed by fire. Just in 1601, the Ottoman rule of the city was interrupted for about one year. Illustrations of the 17th century suggest that the fire and probable blow up was caused by Christian artillery in the course of the Christian conquest.
References:The Church of St Donatus name refers to Donatus of Zadar, who began construction on this church in the 9th century and ended it on the northeastern part of the Roman forum. It is the largest Pre-Romanesque building in Croatia.
The beginning of the building of the church was placed to the second half of the 8th century, and it is supposed to have been completed in the 9th century. The Zadar bishop and diplomat Donat (8th and 9th centuries) is credited with the building of the church. He led the representations of the Dalmatian cities to Constantinople and Charles the Great, which is why this church bears slight resemblance to Charlemagne's court chapels, especially the one in Aachen, and also to the Basilica of San Vitale in Ravenna. It belongs to the Pre-Romanesque architectural period.
The circular church, formerly domed, is 27 m high and is characterised by simplicity and technical primitivism.