The term ‘patriarchate’ with reference to Aquileia can be understood in a double meaning: on the one hand, the ecclesiastical diocese founded in the Roman city, former capital of Venetia et Histria, and guided by its bishop who was rewarded the title of patriarch; on the other hand, the county of Friuli (Comitatus Foriiulii) that in 1077 the Emperor Henry IV gave to the patriarch of Aquileia Sigeard and his successors. The ecclesiastical principality, also known as Patriarchal State, had an autonomous life from 1077 to 1420, while the Aquileian diocese, whose existence is documented since the half of the third century, was suppressed by pope Benedict XIV on 6th July 1751 to be replaced by the two new archdioceses of Udine and Gorizia, the first in the Venetian territory, the second under the Habsburgs’ domain. From a geographic viewpoint the Patriarchal State roughly coincides with current Friuli; the diocese was on the contrary much wider, for it did not only extend over the Italian territory, but above all over the Slovenian and partly also to the Austrian territory. Moreover the patriarchal Church of Aquileia ruled over a much wider ecclesiastical province (metropolis) that included a large number of northern Italian dioceses.