The article analyzes the process of rivalry between two largest cities in Greater Poland, Gniezno and Poznan in the XIII century. During the Middle Ages both cities were the key centers of development of the Greater Poland region. Until the XIII century, there are some reasons to talk about the leading position of Gniezno. However, as a result of a number of factors that paradoxically contributed to the strengthening of Gniezno, in the XIII century Poznan comes to the fore.