The 12th-century late Romanesque church of San Juan Bautista is attached to a 10th-century Berber tower, which is 18 metres tall with a 9.4x7.4 metre floor plan and 1.75-metre thick walls on all of its three floors. Originally it was built with the rammed earth technique but then the structure was changed to stonework. The access door to the tower is hidden in a passageway that connects the tower to the church. Later on, the windows were opened up to place bells inside, and the tower was covered with a roof.
References: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.