First built in the 5th century, St. Simeon's Church has undergone alterations until as recently as 1980, and some find the terracotta and white exterior disappointing in comparison with the other churches. This 17th-century church is best known as the home of the mummified body of St. Simeon, one of Zadar’s patron saints.
The Chest of Saint Simeon is a rectangular cedarwood sarcophagus in the shape of a chasse, overlaid with silver and silver-gilt plaques, said to hold the relics of St Simon the God-receiver; it is located over the main altar in the Church of Saint Simeon. The chest, considered a masterpiece of medieval art and also a unique monument of the goldsmith's craft of the age, is one of the most interesting works in gold in Europe now under the protection of UNESCO. It was made by local goldsmiths to an Italian design between 1377 and 1380.
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.