Following the completion of the new Seoul City Hall in October 2012, it was decided that the old Seoul City Hall should be used as Seoul Library. Upon the annexation of Joseon as a Japanese colony in 1910, the colonists changed the name Hanseong-bu (present-day Seoul) to Gyeongseong-bu, making it part of Gyeonggi-do. To build the Gyeongseong-bu building, along with the Japanese Governor-General’s Office in Korea, Japanese colonists demolished part of a royal palace and spent 6.75 million yen, mobilizing Korean workers for two million man-days over a work period of more than ten years. The building was designed by the Japanese architect Iwazuki Yoshiyuki of the Japanese Governor-General’s Office in Korea. It was built as a three-story (with a basement) Renaissance-style building, in imitatation of the National Diet building of Japan. Special paint was used on the building to withstand the extreme cold weather conditions.