Morphology of the traditional urban open space in Semarang has been turned into commercial space. However, the activities bazaar or informal sector exist to fill the space. Explanation of the phenomenon is not affordable by the place theory from Trancik, and the dualistic theory by Geertz. What is the bazaar open space character of our city? Mixed method, historical and naturalistic methods are used as a research tool. The study's findings are: in the history of the urban open space bazaar events always fill the space. Dualistic condition between the bazaar and modern retail is complementary. Thus the square is the urban open spaces are always filled with activities bazaar.