Sažetak The activities of Bernardin Frankopan (1453-1529), offshoot of important Croatian aristocratic ancestry, were various. He played a diplomatic role, fought in battles against the Turks and managed his estates. In order to defend and protect his estates, Croatian kingdom and, through that, Central Europe in general, Bernardin built a number of fortifications using new renaissance insights in the construction of forts that spread across Europe due to the use of firearms. The first such structures, like Drivenik and Novigrad na Dobri, were erected in the end of the 15th century, whereas other similar ones were built around the year of 1500 and during the first decades of the 16th century. They characteristically featured the basic castle type of plan but varied in elements such as semicircular towers, embrasures, battlements on top of the walls, adjustment of surrounding for defence purposes. Attention was also paid to the safety of daily life by constructing circular residential defence towers. The plans of the castles and their defence system were designed in such a way as to provide every single spot that might be affected by the enemy (i.e. the Turks) with firearm protection from the embrasures of the semicircular towers and battlements on top of the walls. The architecture of the castles depended on the strength of Turkish troops that were expected to attack – raiders, regular army and small armed groups of martoloz (professional military groups of Christian soldiers, volunteers in the Ottoman army). In addition to the basic castle plan, which was either a square or rectangle with semicircular towers on the corners, plans varied and favourable conditions of the terrain were taken into consideration when building castles, though not to such a degree as in the construction of fortifies cities. Regardless of the renaissance principles of building and defence methods, certain details, such as windows, doors, embrasures, corbels and the like were still made in the late Gothic style. It should be stressed that with the escalation of the Turkish aggression, the quality of building and carving was dropping. Stone was more and more replaced by wood as construction material and plans became simplified. The mid-16th century saw the spread of donjon construction, which, was, however, after Bernardin’s age.