This paper describes the photogrammetric 3D modelling of complex buildings using low‐cost automatic image matching (AIM), consumer‐grade digital cameras and low‐altitude imagery. To verify the potential of this method, it was applied to the documentation of a specific case: the towers and roofs of the Cathedral of Santiago de Compostela in Spain, a UNESCO World Heritage Site. The design and development of a mechanism for coping with the elevation, based on telescopic masts, was essential. Models, orthophotos and plans have been obtained to determine and rigorously measure the geometry involved. Thereby it was possible to accurately record the materials and decorative elements based on the restitution of the granite stones. Furthermore, close range photogrammetry made the analysis and quantification of the inclination of the south tower possible.