To respond to the rapid increase of demand for convention facilities according to the expansion of international exchanges and to the changing trend of exhibition pattern held with various conventions such as international conferences and events, the convention annex building with 6 floors and 6 underground floors was constructed at the west of the convention center. By connecting the underground with existing convention center and Coex Intercontinental Hotel at the left and Hotel Oakwood Premier at the right, the convention function was supplemented and at the same time, the international competitiveness as a part of ASEM Complex was secured by installing the facilities that can meet the conveniences and needs of the hotel gusets. In addition, as a landmark at the west of ASEM Complex, the mass of the lower floors and unique elevation that considered the horizontal skyline were generally harmonized with the entire buildings in the complex.