1530, Ferdinand I occupied the castle. He put foreign mercenaries in the castle, and sent the chapter and the bishopric to Nagyszombat and Pozsony (that is why some of the treasury, the archives and the library survived.)
In 1543 Sultan Suleiman I attacked the castle with an enormous army and countless cannons. Following two weeks of heroic struggle of resistance, the foreign (Spanish, Italian and German) guards betrayed the castle. This was the period when the outskirts were finally destroyed. The damaged buildings were not rebuilt again. All means were used to rebuild and strengthen the fortresses or to build new ones. At the same time, the eastern section of the Saint Adalbert Church and other significant buildings of the castle were devastated.
Esztergom (Estergon) became the centre of an Ottoman sanjak controlling several counties, and also a significant castle on the northwest border of the Ottoman Empire – the main clashing point to prevent attacks on the mining towns of the highlands, Vienna and Buda. In 1594, during the unsuccessful but devastating siege by the walls of the Víziváros, Bálint Balassa, the first Hungarian poet who gained European significance, died in action. The most devastating siege took place in 1595 when the castle was reclaimed by the troops of Count Karl von Mansfeld and Count Mátyás Cseszneky. The price that had to be paid, however, was high. Most of the buildings in the castle and the town that had been built in the Middle Ages were destroyed during this period, and there were only uninhabitable, smothered ruins to welcome the liberators.
In 1605 the Ottomans regained control over the castle as well as the whole region again, maintaining their rule until 1683. Though the Ottomans were mainly engaged in building and fortifying the castle, they also built significant new buildings including mosques, minarets and baths. These structures, along with the contemporary buildings, were destroyed in the siege of
