There are numerous gates with glazed components in the Forbidden City in Beijing; they are similar in form, although not identical. Using archival records combined with field mapping data, this paper explores the architectural design of these gates, focusing on the characteristics of the gate body and the components above it. As a direct result, the paper identifies the key dimensions that the builders of the past used for these gates, and elaborates some general principles and rules of their design. This will provide guidance on how to map, document, and conserve these gates in the future.