A dynamic urban system in Spatial Garbage-Can Model (SGCM) is viewed as the outcome of the interaction between a set of elements randomly walking in space. The elements include Decision Makers, Choice Opportunities, Problems, Solutions and Locations. Decision makers, problems, and solutions collide with each other by some unpredictable manner and are thrown into the choice opportunities, or garbage cans, in the particular locations as the main mechanism of the simulation of urban development process (Lai, 2006). This paper attempts to validate externally the SGCM by analyzing three cases in Taipei. In particular, based on the reproduction strategy of multiple case studies through collecting the activity data from Ximending, Xin-Yi Planning District and New Beitou, we conducted the ANOVA analyses to explore into the effects of four structures between the elements on the energy level of the system to verify the results of earlier computer simulations (Lai, 2006). We further calculated the entropies of the structures to observe whether the urban activities in these three places were characterized by self-organization. In addition, we explored into the spatial distribution of these urban activities based on network science. The results of our study were found consistent with the computer simulations: (1) the structural constraints did not have significant effects on the energy level of the system; (2) decision structures tended toward self-organization more significantly when compared with spatial structures; and (3) urban activity network could not be characterized by small-world structures. However, the study did not violate the main observation that institutional design is more effective than spatial design in affecting the urban development process.