In 963 AD Emperor Otto I granted to Adalberto Bishop of Luni ownership of the castrum Sarzanae, a fortified village where today the fortress of Sarzanello is located.
Cittadella or Fortezza Firmafede was the first fortress in the city built in 1249. It was destroyed by the Firenze army led by Lorenzo de Medici in 1487 and rebuilt after the war by Medici. It was reconquered by Genoa Republic in 1494.
Today the massive square form building is used as a venue for culture events and exhibitions.
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.