The significance of Kosice for the revitalization of the Hungarian kingdom in the east and southeast was also reflected in the gradual modernization of the fortifications. In the 16th and 17th centuries, the town became an almost impregnable fortress with three lines of walls and a moat. During the reign of King Leopold I, a star shaped citadel was built in front of the southern gate. Today it can be seen only in contemporary engravings of the town.
Kosice did not escape the religious fighting during Reformation and Counter-Reformation. The churches, including the cathedral of St.Elizabeth, changed hands several times. The religious unrest, the pressure of Turkish armies, the rebelliousness of the Hungarian Estates as well as the loss of leadership of south-north commerce after the shift of world trade centers westwards caused a slump in both commerce and craft production in Kosice and consequently in other east Slovak towns, too. After the Turkish victory, the population in the part of the town encircled by walls dropped by one third compared to the total in 1480. The number of houses was less than four hundred. The erstwhile second largest city in the Hungarian kingdom was stagnating.
Due to the efforts of Benedid Kischdy, the Hungarian Bishop of Eger, the Jesuitical University was established in Kosice in 1657, comprising of philosophical, theological, and linguistic faculties. King Leopold I issued a Golden Bull in 1660 to promote the university and make it equal to other European universities. As a part of the university a printing house was established. The university was changed into a Royal Academy in 1776, and later only the Faculty of Law had the charade of a college. The Jesuitical University Church was built in 1674 - 1684 for needs of the university.
The appearance of the town was altered in the 18th century, when a new building program was embarked on: the suburbs were being founded as the town walls were gradually dismantled. The older palaces and monasteries were redesigned to match the new Baroque and later the classical styles.
