After the change of dynasty on the Frankish throne, the Frankish state experienced its golden age. Not long after Charlemagne came to power, the Franks conquered northern Italy, overthrew the Lombard king and conquered Istria (around 787). The new government brought changes in the social, economic and legal sense (feudal system) and influenced the development of architecture and art. The church and the state are entering a period of closer relations - joint management, that is, the practice of the interference of the secular government in the church government and vice versa. At the beginning, the Franks did not change the internal organization of the Church in Istria, but after an episode of changing loyalty of the Metropolitan of the Church of Istria, Fortunat, the Istrian diocese was separated from the patriarchate in the Grado and submitted to the authority of the Patriarch of Aquileia. In addition to this change, the Frankish government founded new churches, expanded the old ones and intensified construction activity by building new sacred buildings and remodeling old churches according to Frankish models. Carolingian architecture is based on two metaphorical ideas - renovatio and continuatio - which bring back the spirit of the ancient empire to legitimize the Carolingian rule as a legacy of the ancient emperors. The architecture of this era is characterized by the tendency to imitate ancient models and the use of spolia to express legitimacy and equality with the people who previously used this building element. Some elements particularly mark the Carolingian sacral architecture, namely the continuous transept, opposite apses, three-apsidity, crypts and the Carolingian innovation, the westwerk. The biggest impact of this architecture was felt in Istria (compared to the rest of Croatia) because the peninsula became an integral part of the empire as a border province. Through Novigrad, the influence of the Carolingian world reached Istria from Aquileia, which proves the wide distribution of the Carolingian heritage in the province. In this way, Istrian architecture took on the characteristics of the imperial Justinian heritage, the ecclesiastical and political centers of Aquileia and Cividale, and the area of northern Italy. This is proven by various examples throughout Istria, such as the church of St. Mary the Great near Bale, Novigrad Cathedral of St. Pelagia, Church of St. Andrew on Crveni Otok, chapel of St. Andrew as part of the Euphraziana, three-nave basilica of unknown title in Guran and others.