The book explores the history of Justiniana Prima, a city built by Emperor Justinian I (527-565) in his birthplace near Ni in present-day Serbia. Previous studies focused on determining the city's location, underestimating the significance of analyzing written sources for the reconstruction of this city's genesis and importance. Using information from Emperor Justinian's Novels XI and CXXXI, as well as Book IV of Procopius of Caesarea's De aedificiis, Stanislaw Turlej endeavors to show that Justiniana Prima's historic significance resulted from granting its Church the status of an archbishopric with its own province in 535, which was independent of Rome. Justinian wanted to introduce profound changes to the ecclesiastical organization based on state law.