Urbanization is global and historical process that represents evolution and development of cities. Cities are connected with each other, and together create urban sistems of different sizes and characteristics. Africa is the lowest urbanized continent, but there are present great regional differences in scale of urbanization and nubmer of cities. Throughout Africa societies that had been predominantly rural for most of their history were experiencing a rapid and profound reorientation of their social and economic lives toward cities and urbanism. As ever greater numbers of people moved to a small number of rapidly expanding cities, the fabric of life in both urban and rural areas changed in massive. With the largest and one of the most rapidly growing cities in sub-Saharan Africa, Nigeria has experienced the phenomenon of urbanization as thoroughly as any African nation. In development of urban system in Nigeria three historical periods have had big importance: precolonial, colonial and postcolonijal periods. Each period contributed nowdays dimension of urban sistem. The most profound efects are from colonial peroid. Nigeria has very dense network of cities, although Lagos dominates there are big and significant cities in other parts of the state.