This manuscript emerged as the result of a study of the sources on Levý Hradec, an important hillfort closely connected with the beginning of Early Mediaeval Czech state, during the archaeological excavations from the half of the 19th century till today(especially excavations of I. Borkovský). Main areas of interest are: 1. bailey of Levý Hradec, its fortification and settlement, 2. selected questions of archaeological study of acropolis, including first publication of sources for knowledge of the building interpreted as a duke_s palace, 3. development of the Church of St. Kliment, the oldest Christian church in Bohemia in the light of archaelogical and written sources, 4. tradidion of Levý Hradec as a place "where the Christianity was born". The bookis dealing mainly an critical evaluatuin of field situation, which forms the base for more precise reconstruction of the development of bailey_s fortification as well as of whole site.