The Roccella Ionica Castle sits on a rocky promontory at 104 meters, overlooking the village. Founded during the Norman period by Gualtieri De Collepietro, it later passed to the Ruffo family, then to Galeotto Baldaxi, and finally to the Carafa della Spina family, who restored it between 1479 and 1806. The fortress withstood attacks, including from Turkish corsair Dragut Pasha in 1553. The palace features ruins, including a stone portal with the Carafa crest, a monumental balcony with carved figures, and a courtyard with a star-shaped drainage system. Next to the castle is the Baroque-style Mother Church of St. Nicholas, once connected to the palace by a private choir. The church houses valuable polychrome marble altars, now national monuments.
The Church of St Donatus name refers to Donatus of Zadar, who began construction on this church in the 9th century and ended it on the northeastern part of the Roman forum. It is the largest Pre-Romanesque building in Croatia.
The beginning of the building of the church was placed to the second half of the 8th century, and it is supposed to have been completed in the 9th century. The Zadar bishop and diplomat Donat (8th and 9th centuries) is credited with the building of the church. He led the representations of the Dalmatian cities to Constantinople and Charles the Great, which is why this church bears slight resemblance to Charlemagne's court chapels, especially the one in Aachen, and also to the Basilica of San Vitale in Ravenna. It belongs to the Pre-Romanesque architectural period.
The circular church, formerly domed, is 27 m high and is characterised by simplicity and technical primitivism.