Frankopan-Zrinski Castle, Kraljevica

Two Frankopan-and-Zrinski castles for the price of one in this small harbour town at the base of the Krk Bridge — a fact locals are quick to remind you. The larger 'New Castle' (Novi Grad) is a superb example of late-Renaissance military architecture, built by the Zrinski family between 1650 and 1657 as a fortified residence and command post for their newly created port and shipyard, at a moment when the Zrinski dynasty was briefly the most powerful noble family in Croatia. Its four squat corner bastions were designed to withstand cannon fire, its interior courtyard flanked by two-storey arcaded loggias where the family lived. The tragic denouement came in 1671, when Petar Zrinski and his brother-in-law Fran Krsto Frankopan were executed in Vienna after a failed anti-Habsburg conspiracy; the castle was confiscated, gradually abandoned, and only partially restored in the 21st century. Today it hosts a small museum tracing the Zrinski story, temporary art exhibitions, and one of the most atmospheric summer concert stages on the Kvarner. The smaller Old Castle (Stari Grad), on a rise above the harbour, is a 15th-century Frankopan fortress with its own smaller collection. Combine the two in a two-hour visit, then walk down for lunch at the harbour and a swim at Oštro beach on the peninsula tip.