Construction projects are usually characterised by their large scale, complicated technologies, long periods of time to complete, and challenging collaboration efforts. The provision of digital representations that combine physical properties with geospatial information can help to solve some of these problems. Thus, the current study proposes a novel approach of integrating building information modelling (BIM) into the geographic information system (GIS) domain as a way of combining micro- and macro-level information into a unified domain without needing to convert between data standards or use any intermediate format. Moreover, this study provides an approach to automatic geo-referencing of the BIM model in the GIS domain without prior knowledge of the corresponding points. Based on the proposed integration approach, an integrated BIM+GIS web-based platform was developed that allows various stakeholders access to project information from different geographical areas, thereby enhancing information sharing and facilitating project management. To evaluate the functions and feasibility of the developed platform, it was employed for managing a mega construction project. The results indicate that the process of integrating BIM into the GIS domain was accurate and effective, and the developed platform can help to properly manage a mega-project by providing the required information and functions.