from Wikipedia Seoul:
Seoul (listen IPA: [sʌul]) is the capital and largest city of South Korea. With over ten million people, Seoul is one of the world's largest cities. It is also the world's second largest metropolitan area, the Seoul National Capital Area - which includes the major port city of Incheon and satellite towns in Gyeonggi-do, having almost 23 million inhabitants. Almost half of South Korea's population lives in the Seoul National Capital Area, and nearly one quarter in Seoul itself, making it the country's political, cultural, and economic centre. As a Special City, it is administered directly by the national government.
The city is located on the basin of the Han River in the country's northwest. The North Korean border lies about 50 km to the north.
Seoul first appears in history in 18 BC, when the Baekje kingdom established its capital Wiryeseong in what is now around Songpa-gu, southeastern Seoul. Modern Seoul descends from the Goryeo-era city called Namgyeong, which then became the capital of Korea during the Joseon dynasty.
As a major financial and cultural center, Seoul is considered a global city. The city has hosted the 1988 Summer Olympics and the 2002 FIFA World Cup. In 2007, it was listed as the third most expensive city in the world and the most expensive in Asia.
In recent years, the Seoul Metropolitan Government has undertaken major environmental projects, including the nearly $1 billion restoration of Cheonggyecheon. At the same time, the city has promoted the Seoul Digital Media City, the world's first complex for high-tech digital technologies in multi-media, IT, and entertainment, and the proposed future site of the world's second tallest building.