Building design process is a significantly complex procedure taking into account many different factors and variables, such as the site context, environment, material availability, cost, and function. One of the most complex forms in the built environment is tall building because of the scale, design considerations, and multidisciplinary nature. This article discusses development of ontological model for understanding, presenting, relating, and managing knowledge influencing architectural design of tall buildings. Ontology is a knowledge-based model that represents certain domain by abstraction of concepts, and a network of relationships and properties describing these concepts. By creating an architectural ontology, the factors, relations, and characteristics in the design process can be clearly defined and presented. The model incorporates physical systems such as structure, building elements, and geometry, as well as environmental effects, social aspects and other complex attributes.