High on a hill above the city, this semiruined 13th-century fortress offers magnificent vistas from its bastions and ramparts, looking down the Rječina river valley to the docks, the Adriatic and the distant island of Krk. The present structure was built by the Frankopan dukes of Krk, but its latest facelift was in 1824 when Irish-born count Laval Nugent, a commander in the Austrian army, bought the castle and had it restored in a romantic neoclassical Biedermeier design.

Guarded by basilisks, the Ancient Greek–style Nugent family mausoleum houses a gallery, while underground a former dungeon hosts occasional exhibits. During summer, the fortress features concerts, theatre performances and fashion shows. The open-air cafe-bar (open until midnight in summer) is a wonderful spot to take in the views.