Seoul is the capital and largest city of South Korea. A megacity with a population of over 10 million, it is one of the largest cities in the world. The Seoul National Capital Area is the world's second largest metropolitan area with over 24.5 million inhabitants, which includes the Incheon metropolis and most of Gyeonggi. Almost half of South Korea's population live in the Seoul National Capital Area, and nearly a quarter in Seoul itself, making it the country's foremost economic, political, and cultural center. province.

Seoul has been a major settlement for over 2,000 years, with its foundation dating back to 18 B.C. when Baekje, one of the Three Kingdoms of Korea, established its capital in what is now south-east Seoul. It continued as the capital of Korea during the Joseon Dynasty and the Korean Empire. The Seoul National Capital Area is home to four UNESCO World Heritage Sites: Changdeokgung, Hwaseong Fortress, Jongmyo Shrine and the Royal Tombs of the Joseon Dynasty.

Today, Seoul is considered to be a leading global city, ranking among the top ten global cities in the Global Cities Index of 2010. It is one of the world's top ten financial and commercial centers, home to major multinational conglomerates such as Samsung, LG and Hyundai-Kia. In 2008, Seoul was named the world's sixth most economically powerful city by Forbes.

Seoul has a highly technologically advanced infrastructure. Its Digital Media City is the world's first complex for IT and multimedia applications. Seoul was the first city to feature DMB, a digital mobile TV technology and WiBro, a wireless high-speed mobile internet service. It has a fast, high-penetration 100Mbps fibre-optic Seoul Station houses the 350 km/h KTX bullet train and the Seoul Subway is the third largest in the world, with over 200 million passengers every year. Seoul is connected via AREX to Incheon International Airport, rated as the best airport in the world by Airports Council International. broadband network, which is being upgraded to 1Gbps by 2012.

Seoul is in the northwest of South Korea. Seoul proper comprises 605.25 km², with a radius of approximately 15 km, roughly bisected into northern and southern halves by the Han River. The Han River and its surrounding area played an important role in Korean history. The Three Kingdoms of Korea strove to take control of this land, where the river was used as a trade route to China (via the Yellow Sea). However, the river is no longer actively used for navigation, because its estuary is located at the borders of the two Koreas, with civilian entry barred. The city is bordered by eight mountains, as well as the more level lands of the Han River plain and western areas.

Climate

Seoul lies in the border region between a humid subtropical and humid continental climate (Köppen climate classification Cwa/Dwa), depending on the definition. Summers are generally hot and humid, with the East Asian monsoon taking place from June until July. August, the warmest month, has an average temperature of 22.1 to 29.5 °C (72 to 85 °F) with higher temperatures possible. Winters are often relatively cold with an average January temperature of -6.1 to 1.6 °C (21 to 34.9 °F) and are generally much drier than summers, with an average of 28 days of snow annually.

Transportation

Seoul's transportation system dates back to the era of the Korean Empire, when the first streetcar lines were laid and a railroad linking Seoul and Incheon was completed. Seoul's most important streetcar line ran along Jongno until it was replaced by Line 1 of the subway system in the early 1970s. Other notable streets in downtown Seoul include Euljiro, Teheranno, Sejongno, Chungmuro, Yulgongno, and Toegyero. There are nine major subway lines stretching for more than 250 kilometers, with one additional line planned.

Seoul has more than three million registered vehicles and suffers from widespread traffic congestion.

Bus

Seoul's bus system is operated by the Seoul Metropolitan Government, with four primary bus configurations available servicing most of the city. Seoul has many large intercity/express bus terminals. These buses connect Seoul with cities throughout South Korea. The Seoul Express Bus Terminal, Central City Terminal and Seoul Nambu Terminal are located in the district of Seocho-gu. In addition, East Seoul Bus Terminal in Gwangjin-gu and Sangbong Terminal in Jungnang-gu operate in the east of the city. To reduce air pollution in the metropolitan area, the municipal government is planning to convert over seven thousand of Seoul's diesel engine buses to natural gas by 2010.

Subway

Seoul Station.

Seoul has a comprehensive subway network that interconnects every district of the city and the surrounding areas. With more than 8 million passengers per day, Seoul has one of the busiest subway systems in the world. The Seoul Metropolitan Subway has 12 lines which serve Seoul, Incheon, Gyeonggi province and northern Chungnam province. In addition, in order to cope with the various modes of transport, Seoul's metropolitan government employs several mathematicians to coordinate the subway, bus, and traffic schedules into one timetable. The various lines are run by Korail, Seoul Metro, Seoul Metropolitan Rapid Transit Corporation, AREX and Metro 9

Train

Seoul is connected to every major city in Korea by rail. Seoul is also linked to most major Korean cities by the KTX high-speed train, which has a normal operation speed of more than 300 km/h (186 mph). Major railroad stations include:

• Seoul Station, Jung-gu: Gyeongbu line (KTX/Saemaul/Mugunghwa-ho), Gyeongui line (Saemaul/Commuter)
• Yongsan Station, Yongsan-gu: Honam line (KTX/Saemaul/Mugunghwa), Jeolla/Janghang lines (Saemaul/Mugunghwa)
• Yeongdeungpo Station, Yeongdeungpo-gu: Gyeongbu/Honam/Janghang lines (Saemaul/Mugunghwa)
• Cheongnyangni Station, Dongdaemun-gu: Gyeongchun/Jungang/Yeongdong/Taebaek lines (Mugunghwa)

Airports

Incheon International Airport.

Two international airports serve Seoul. Gimpo International Airport, formerly in Gimpo but annexed to Seoul in 1963, was for many years (since its original construction during the Korean War) the only international airport serving Seoul. Other domestic airports were also built around the time of the war, including Yeouido.

When it opened in March 2001, Incheon International Airport on Yeongjong island in Incheon changed the role of Gimpo Airport significantly. Incheon is now responsible for almost all international flights and some domestic flights, while Gimpo serves only domestic flights with the exception of flights to Tokyo International Airport (Haneda) in Tokyo, Osaka Kansai International Airport and Hongqiao Airport in Shanghai. This has led to a significant drop in flights from Gimpo Airport.

Meanwhile, Incheon International Airport has become, along with Hong Kong, a major transportation center for East Asia.

Incheon and Gimpo are linked to Seoul by highways, and to each other by the Incheon International Airport Railroad, which is also linked to Incheon line #1. Gimpo is also linked by subway (line #5 and #9). The Incheon International Airport Railroad, currently under construction, is planned to connect the airport directly to Seoul Station in central Seoul but will not be completed for several years. Shuttle buses also transfer passengers between Incheon and Gimpo airports.