The South Korean capital is Seoul, which is a five-letter word. Seoul is the largest city and capital of South Korea, located on the Han River in the northwest of the country. It is the world's sixth-largest metropolitan area and the second-largest in Asia. Seoul has been the capital of Korea since 1394 and is home to over 10 million people. It is a major economic, political, and cultural center of the country and is known for its vibrant nightlife and modern architecture.