The Zrinski Castle — also called the New Castle or Frankopan-Zrinski Castle — was built between 1626 and 1652 by Petar Zrinski and Fran Krsto Frankopan, the brothers-in-law who would later lead the failed Magnate Conspiracy against Habsburg Vienna. It is a substantial Renaissance fortress with four corner towers, an inner courtyard, and the family chapel of Sts Peter and Paul. After the conspirators were executed in 1671 the castle passed to the Habsburg crown, and it later served as a hospital, school, and barracks.
The castle has been undergoing restoration; check current opening hours before counting on a guided interior visit. The exterior and courtyard can usually be seen on foot.