This book reinterprets architecture in Beijing during the reigns of the Kangxi (1661-1722), Yongzheng (1723-1735) and Qianlong (1736-1795) emperors in the eighteenth-century. More specifically, it views the building processes of the four churches and the Western palaces in the Yuanming Yuan garden as an example of cultural dialogue in the context of the Enlightenment. The study is based firstly on archival sources from different institutions from around the globe using Big Data to manage them. Secondly, it places increased emphasis on architectural remains, preserved both in international collections as well as at archaeological sites. To take advantage of these remains, some were recorded using close-range photogrammetry. Digital sunlight analyses of the buildings’ interiors were also carried out. From these emerging technologies, as well as written sources, it becomes possible first to reinterpret Beijing as an imperial capital where religious tolerance and cosmopolitanism were increasing, and second to re-evaluate the entire Yuanming Yuan Garden complex as a miniature version of Beijing. This approach makes for easier subsequent comparisons with other imperial capitals of the time, such as London, Paris and Istanbul. As such, this study reveals a largely neglected chapter in the global history of architecture, while simultaneously offering a crucial re-examination of the existing architectural remains.