The Udine castle hill is made of drift accumulating during centuries. However, a legend about its origin says that when Attila the Hun (also called the Scourge of God) plundered Aquileia (one of the biggest cities of the Roman Empire at that time) in the year 452, he asked his soldiers to build a hill to see the Aquileia burning. This was made by filling the helmet of each soldier with ground.
The first official statement of the existence of a building on the hill dates back to 983: the Holy Roman Emperor Otto II donated to Rodoaldo, Patriarch of Aquileia a castrum, a military building.
The present building has the form of a palace and it was built on the ruins of a fortress destroyed in the year 1511 Idrija earthquake. The construction had started in 1517 and the works had lasted for 50 years. The external decoration of the palace and the paintings in the Parliament Hall are due to Giovanni da Udine, one of the pupils of Raphael.
The council of the Patria del Friuli was one of the first parliaments in the world, and it was suppressed after the French occupation in 1797.
Today the castle hosts the History and Art Museum of the City of Udine.
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.