The plaza area at the Great Mosque of Central Java is a non-green open space of the Central Java Grand Mosque building complex. The Plaza area has an important role in the building, because the plaza area at the mosque is the first place we meet, and becomes the center of circulation and socio-religious activities for visitors. Thus, it is necessary to design a plaza area at the Grand Mosque of Central Java which considers all aspects. Open space has a role as a container that can accommodate certain activities of the community in certain areas, therefore open space has a contribution to be given to humans in the form of positive impacts. This research was conducted at the Grand Mosque of Central Java using qualitative-descriptive methods. This research focuses on studies in the plaza area of the Grand Mosque of Central Java in terms of open space functions. The results of this study, in the plaza area at the Great Mosque of Central Java, show that it has not fulfilled both as a general function of open space and an ecological function.