A central pursuit of micro-and nano-scale engineering is describing the small-scale structure of materials in terms of spatial relationships between positions of particles (representing, e.g., individual atoms). In order to carry out such analyses, molecular simulation practitioners have developed a large array of fast methods to compute spatial relationships on particle-resolved data sets. We have developed a computational workflow that directly applies molecular simulation methods to GIS building data, in which individual buildings (instead of, e.g., atoms) are treated as the particles of interest. In so doing, we enable efficient quantification of "urban textures" consisting of ≫ O (10 3) buildings. This interdisciplinary toolkit potentially opens the door to new vistas for urban-systems modeling. As one of a few early examples, we provide evidence for a novel scaling relationship between size and ordinal rank of building clusters within several American cities, reminiscent of Zipf's Law. This scaling relation suggests a new perspective on fractal-like organization of urban environments.