The purpose of this study is to understand the architectural changes that occurred in the main space of Deoksugung Palace based on the 『Deoksugung Wonan』. In the 1910s, constructions in the Deokhongjeon area and Hamnyeongjeon area caused a change in the main space of Deoksugung Palace, which is similar to the change in the central space of Changdeokgung Palace. In both palaces, the space composition, architectural structure, construction equipment, and architectural design of the palace were changed due to the changed architectural organization and construction system.

This study aims to reinterpret Jeonggwanheon(靜觀軒) in terms of its use and architectural style after restoration work through the recently discovered [Deoksugung Palace's original plan](1915). It is presupposed that the existing interpretation of Jeonggwanheon, such as its status as the banquet hall of the Imperial Empire and the place where Emperor Gojong enjoyed coffee here, was a fantasy made from the transformation after the 1930s. When it was built around 1900, Jeonggwanheon arranged small and large rooms around the corridor in the center, and the porch surrounded the three sides of the building. From 1900 to 1907, there is no remaining record telling us who did what or when something happened in Jeonggwanheon except for several portraits of Emperor Gojong and his son which were drawn in 1902. The mixed use of brickwork and wooden porch are found in many of American style houses built in Incheon and Seoul at that time. Especially, the style and decoration of wooden porch seem to be influenced by Queen Anne style in the 19th century in America.

Deoksugung Palace Art Museum was built in 1938 as the first professional art museum in Korea. In 2015, National Research Institute of Cultural Heritage published a book on architectural drawings of this building. This book, called Architectural Drawings of the Deoksugung Palace Art Museum, consists of 646 sheets, 23 types of documents, as well as other historical letters. This paper focuses on the analysis of the characteristics of classicism in Architectural Drawings. It shows that every dimensions of drawings were controled by 3 partition composition through the analysis of architectural plan drawings, elevation drawings and even section drawings. Thus, Classicism for the museum is not about classical elements but the principle of composition of each elements for the construction. This paper further argues that Deoksugung Palace Art Museum exemplifies beautiful Classicism architecture which follows the principle of classical architectural composition.