Historic castle ruins represent significant examples of cultural heritage and are simultaneously part of complex ecological systems. However, climate change, increasing weather extremes, vegetation growth, and natural succession processes pose new challenges for their long-term preservation. The aim of this project was to develop an integrated approach that combines digital documentation, ecological assessment, and conservation strategies. Within the project, the Montfort and Schmidtburg castle ruins were examined as equivalent case studies. Both sites were documented using LiDAR scanning and photogrammetry and subsequently converted into Heritage Building Information Models (HBIM). The digital models serve not only for geometric documentation but also form a basis for damage mapping, ecological analyses, and future conservation measures. A key component of the project was close collaboration with experts in the fields of historic preservation, stone conservation, and nature conservation. Based on this collaboration, methods for mapping damage to natural stone and recommendations for managing vegetation within historic masonry structures were developed. In addition, a Common Data Environment (CDE) was established, enabling the exchange of models, documentation, and comments between different disciplines. Furthermore, the project results were successfully integrated into teaching at Mainz University of Applied Sciences. Based on the digital models, students developed sustainable designs for temporary shelters („Eco Shelters“) for castle ruins. Overall, the project demonstrates that HBIM, in conjunction with ecological analyses, standardized information processes, and interdisciplinary collaboration, represents a promising approach for the sustainable preservation of historic castle ruins.