Urban planning data are critical for civil engineers, architects, urban planners, and the general public. However, the scattered and heterogeneous nature of these datasets, encompassing both geographical and taxonomical knowledge, poses significant challenges for integration and meaningful analysis. This paper presents an ontology-based framework tailored for the integration of urban planning data, with a specific focus on civil engineering applications in the City of Prague. I examine the domain’s ontological structure and formalize the ontology using the OWL language, addressing semantic inconsistencies in core concepts such as “building,” “construction,” and “infrastructure.” By leveraging this framework, I enable advanced distributed queries over multiple datasets, improving data accessibility, consistency, and usability for urban development and civil engineering projects.