Trsat Castle, Medieval fortress in Sušak, Croatia.

Trsat Castle consists of a round stone tower with crenellations and, attached to its right, a rectangular structure with a pedimented roof bearing the inscription MIRIJUNAKA. Four columns support the roof above a stone wall with rectangular windows. The castle stands on a 138-metre hill above the Rječina gorge, and its courtyard now holds a restaurant.

The Frankopans built the present castle in the 13th century to protect their Vinodol holdings, on a site used since Roman times above the Rječina. In 1509 Ban Andrew Bot of Bajna retook it from the Venetians and then entered Rijeka. After decay and the 1750 earthquake, Count Laval Nugent bought it in 1826 and had architect Pavonuzzi rebuild it from 1827 as a castle-residence, erasing its medieval features.

The castle's name appears in the inscription MIRIJUNAKA across the pediment of the entrance building. In 1843 the Nugent museum opened inside the castle, the first museum in Croatia at the time. Since 1964 part of the complex has housed a restaurant, and an open-air stage is used for performances.

The castle stands on a 138-metre hill above the Rječina bend, northwest of Trsat. The complex has two parts: the front section at the entrance and the rear section rising on the north side. The oldest part, the Frankopan Tower, occupies the southwest corner. Part of the complex was converted into a restaurant in 1964, and an open-air stage now operates there.

The castle's oldest element, the Frankopan Tower in the southwest corner, is traditionally said to stand on the foundations of a Roman watchtower, which is why it is also called the Roman Tower. In the Middle Ages it served as a residential tower; only its lower part is original, the upper section dating from the 19th-century reconstruction.