Torre di Federico is an octagonal ancient tower that was allegedly a summer residence of Frederick II of Hohenstaufen. The two floors possess beautiful vaults. The aspect of the building is austere. It was part of a bigger complex, named Old castle and destroyed by Arabs. Remnants include some pieces of the old, imposing walls on the top of the green hill where the Tower rises.
The tower is an imposing 26 metres high, has a diameter of 17 metres and its walls are 3.5 metres thick.
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.