The Emperor's Palace in Milan was founded in about 291 AD by emperor Diocletian. Here Constantine and Licinius issued the Edict of Milan in 313 AD.
Residential and ambassadorial sectors, private baths and the circus, where the Emperor appeared solemnly to his subjects, and victory in chariot races became symbolic of Imperial victories, took up an entire sector of the city. The only visible traces of this vast polyfunctional quarter, which stayed in use perhaps up until the tenth century, are the remains of an ambassadorial building which had central heating; many archaeological remains are probably to be found under the buildings around Via Brisa.
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.