The Hungarian army was destroyed at Mohács on 29 August 1526, and within twenty years the Ottomans held the middle of the country and the Danube had become a front line. In 1546 Ferdinand I's engineers began rebuilding the castle as a modern Italian-style bastion fort — low, thick, angled walls that cannonballs bounce off instead of knocking down; the Italian architect Pietro Ferrabosco was one of the designers. This is the Old Fortress, and it was tested in 1594, when an Ottoman army reported at a hundred thousand men besieged it and failed to take it. It had done exactly what it was built to do.29. augusta 1526 padlo uhorské vojsko pri Moháči a do dvadsiatich rokov Osmani ovládli stred krajiny — Dunaj sa stal frontovou líniou. Roku 1546 začali inžinieri Ferdinanda I. prestavovať komárňanský hrad na modernú bastiónovú pevnosť talianskeho typu: nízke, hrubé, šikmé múry, od ktorých sa delové gule odrážajú, namiesto toho, aby ich rozbíjali; jedným z projektantov bol Talian Pietro Ferrabosco. Takto vznikla Stará pevnosť a skúšku dostala roku 1594, keď ju obliehalo osmanské vojsko, o ktorom sa písalo, že malo stotisíc mužov — a nedobylo ju. Urobila presne to, na čo bola postavená.
