Photogrammetry is a digital technique that uses 2D images to create 3D models, which has various applications in cultural heritage such as documentation, digital tourism, and restoration, which mainly focus on current and future needs. However, there is limited literature regarding on how photogrammetry can be used for better research of architectural history. Photogrammetry is a potential tool to obtain a comprehensive exploration of the past. A more comprehensive exploration of the past will certainly have an impact on the sustainable regeneration of architectural heritage. Therefore, this paper aims to bring forward digital application as a research method of historical interpretation by using photogrammetry. The research implemented the photogrammetric method to investigate the site of 'UNESCO Foguang Monastery' in China by collecting aerial photographs using drone, then employed Reality Capture software to create a 3D model of the mountain monastery. Through this 3D model of the monastery and its vicinity, the artificial gullies around the enclosed courtyard, as a part of religious landscape, were discovered for the first time by the author. This discovery promotes the understanding of religious landscape history because the gullies create land boundaries and define the sacred place that presents Buddhist cosmology. This finding indicates that in transforming a common land into a sacred site, Buddhists not only erected monastic monuments, but also considered the religious landscape. This study also aims to inspire historical architecture researchers to employ digital methods and broaden their perspective on surveying architectural heritage, particularly in relation to their landscape scale.