This study shows the characteristics of the early phenomena of the city plan Hanyang (old city Seoul). It consists of two steps. One is to search for the constructing principles of the geometric setting. And the other is to inquire and interpret the objects of beginning and ending points of that setting. The results based on geographic analysis and historical facts are as follows: 1) The city plan Hanyang shows a certain hierarchy:the major axis and the locations of the palace and the city set up in the prority. This priority made onto lower hierarchical plans such as the site plans of palaces and city wall. For example of the significant objects are Namdaemum (South Gate of the city wall) and Kwanghwamun (South Gate of the Palace). They are on the main axis, and became the basic points of the detailed city plans. 2) The palace palace on its major axis, right-angled minor axis, and 4 grade inclination to north. The four small city wall gates located on the base of four greater gates. 3) The geometric characteristics as constructing principle found on certain hierarchical order. Thus, the natural elements as mountains, had an important effect on the arrangement of major facilities and those main constructions made on lower - hierarchical settings. 4) These facts related closely to the philosophy of Jung, Do-Jon, the initiative planer of the Hanyang.