Hyundai Motors Ulsan Plant is the world's largest single plant. It is made up of five independent factories, with approximately 32,000 personnel producing an average of 1,520,000 vehicles per year. The complex is 1.5 times bigger than the area of Yeouido, and owns a port where they ship out maximum of 4,500 vehicles per day.
Source: Korea Tourism Organization official English tourism database. Opening hours and details can change — check the official website before visiting.