While recent years have witnessed noticeable development of indoor GIS, there is still a lack of clear consensus on the modeling principles that should support such applications. The objective of the research presented in this paper is to represent two-dimensional (2D) indoor spaces with a grid graph-based model that takes into account the structural and spatial properties of an indoor space. The model developed considers a built environment as a frame of reference at different levels of granularity using a grid graph-based representation. The advantage of the modeling approach is that it combines structural and topological properties as well as implicitly taking into account the metric of space, this being often overlooked by most existing indoor space models. Several types of indoor space analysis are employed to illustrate the potential of the proposed model, such as route and diffusion analysis, centrality and topological analysis.