Seoul, officially Seoul Special Metropolitan City, is the capital and largest city of South Korea, and the largest city in the whole of Korea. The broader Seoul Metropolitan Area, encompassing Seoul, Gyeonggi Province and Incheon, emerged as the world's sixth largest metropolitan economy in 2022, behind New York, Tokyo, Los Angeles, Paris, and London, and hosts more than half of South Korea's population. Although Seoul's population peaked at over 10 million, it has gradually decreased since 2014, standing at about 9.6 million residents as of 2024.
Seoul's history traces back to 18 BC when it was founded by the people of Baekje, one of the Three Kingdoms of Korea. During the Joseon dynasty, Seoul was officially designated as the capital, surrounded by the Fortress Wall of Seoul. In the early 20th century, Seoul was occupied by the Empire of Japan, temporarily renamed "Keijō" ("Gyeongseong" in Korean). The Korean War brought fierce battles, with Seoul changing hands four times and leaving the city mostly in ruins. Nevertheless, the city has since undergone significant reconstruction and rapid urbanization.
The de facto administrative capital has gradually switched to the planned city of Sejong City, which opened in 2012 and is located about 121 kilometers further south. As of 2019, Sejong hosts 10 out of the South Korean government's 18 ministries. Despite this, the Constitutional Court of Korea declared in 2004 that Seoul must remain the national capital due to it being an "unwritten constitutional custom", unless otherwise changed by a nationwide referendum.
Seoul was rated Asia's most livable city, with the second-highest quality of life globally according to Arcadis in 2015 and a GDP per capita (PPP) of approximately $40,000. 15 Fortune Global 500 companies, including industry giants such as Samsung, LG, and Hyundai, are headquartered in the Seoul Capital Area, which has major technology hubs, such as Gangnam and Digital Media City. Seoul is ranked seventh in the Global Power City Index and the Global Financial Centres Index, and is one of the five leading hosts of global conferences. The city has also hosted major events such as the 1986 Asian Games, the 1988 Summer Olympics, and the 2010 G20 Seoul summit, in addition to three matches at the 2002 FIFA World Cup.
Seoul is geographically set in a mountainous and hilly terrain, with Bukhansan positioned on its northern edge. Within the Seoul Capital Area lie five UNESCO World Heritage Sites: Changdeokgung, Hwaseong Fortress, Jongmyo, Namhansanseong, and the Royal Tombs of the Joseon dynasty. Furthermore, Seoul has witnessed a surge in modern architectural development, with iconic landmarks including the N Seoul Tower, the 63 Building, the Lotte World Tower, the Dongdaemun Design Plaza, Lotte World, the Trade Tower, COEX, IFC Seoul, and Parc1. Seoul was named World Design Capital 2010 and has served as the national hub for the music, entertainment, and cultural industries that have propelled K-pop and the Korean Wave to international prominence.
Traditionally, seoul (서울) has been a native Korean (as opposed to Sino-Korean) common noun simply meaning 'capital city.' The word seoul is believed to have descended from Seorabeol (서라벌; historically transliterated into the Hanja form 徐羅伐), which originally referred to Gyeongju, the capital of Silla.
Wiryeseong (위례성; 慰禮城), the capital settlement of Baekje, was located within the boundaries of modern-day Seoul. Seoul was also known by other various historical names, such as Bukhansan-gun (북한산군; 北漢山郡, during the Goguryeo era), Namcheon (남천; 南川, during the Silla era), Hanyang (한양; 漢陽, during the Northern and Southern States period), Namgyeong (남경; 南京, during the Goryeo era), and Hanseong (한성; 漢城, during the Joseon era). The word seoul was used colloquially to refer to the capital as early as the 17th century. Thus, the Joseon capital of Hanseong was widely referred to as the seoul. Due to its common usage, French missionaries called the Joseon capital Séoul (/se.ul/) in their writings, hence the common romanization Seoul in various languages today.
Under subsequent Japanese colonization, Hanseong was renamed Keijō (京城, literally 'capital city') by the Imperial authorities to prevent confusion with the hanja 漢 (a transliteration of a native Korean word 한; han; lit. 'great'), which may also refer to the Han people or the Han dynasty in Chinese and is associated with China in Japanese context. After World War II and the liberation of Korea, Seoul became the official name for the Korean capital. The Standard Korean Language Dictionary still acknowledges both common and proper noun definitions of seoul.
Unlike most place names in Korea, as it is not a Sino-Korean word, Seoul has no inherently corresponding Hanja (Chinese characters used in the Korean language). Instead of phonetically transcribing Seoul to Chinese, in the Chinese-speaking world, Seoul was called Hànchéng (汉城; 漢城), which is the Chinese pronunciation of Hanseong. On 18 January 2005, the Seoul Metropolitan Government changed Seoul's official Chinese name from the historic Hànchéng to Shǒu'ěr (首尔; 首爾). Shǒu'ěr is a phono-semantic match incorporating both sound and meaning (through 首 meaning 'head', 'chief', 'first').
There is evidence of human habitation in the area now corresponding to Seoul from 30,000 to 40,000 years before the present. Around 4,000 B.C., people of the area lived in huts with lowered floors called umjip. There is evidence of the consumption of cooked grain and fish by 3,000 B.C. Around 1,500 B.C., communities began transitioning into the Bronze Age and farming at scale.
Due to modern Seoul's significant urbanization, Amsa-dong Prehistoric Site is the only known major archaeological site in Seoul where Stone Age materials have been found, although such materials have also been found in minor sites throughout the city (and all around the surrounding Han River basin), often through rescue archaeology.
Around the collapse of Wiman Joseon (194–108 B.C.) in the northern part of Korea, numerous refugees went south to the Han River basin, which was then controlled by Jin (4th–2nd century B.C.). These diverse peoples brought with them culture and technology of the Chinese Warring States that accelerated the region's progress into the Iron Age. Their arrival destabilized the region; Jin disintegrated, and dozens of statelets emerged that competed for influence in the Han River basin.
Baekje (18 B.C. – 660 A.D.), once one of the statelets in the Mahan confederacy, became the dominant local power by the 2nd century A.D. Its capital was in Wiryeseong; Wiryeseong specific location is not known with certainty, but it is believed to have been within the bounds of the ramparts P'ungnapt'osŏng and Mongchontoseong. This area is now in southeastern Seoul.
In July or August 553, Silla took the control of the region from Baekje, and the city became a part of newly established Sin Province (신주; 新州). Sin (新) has both meaning of "New" and "Silla", thus literally means New Silla Province.
In November 555, Jinheung Taewang made a royal visit to Bukhansan, and inspected the frontier. In 557, Silla abolished Sin Province, and established Bukhansan Province (북한산주; 北漢山州). The word Hanseong (한성; 漢城; lit. 'Han Fortress') appears on the stone wall of "Pyongyang Fortress", which was presumably built in the mid to late 6th century AD over period of 42 years, located in Pyongyang, while there is no evidence that Seoul had name Hanseong dating the three kingdoms and earlier period.
In 568, Jinheung Taewang made another royal visit to the northern border, visited Hanseong, and stayed in Namcheon on his way back to the capital. During his stay, he set Jinheung Taewang Stele, abolished Bukhansan Province, and established Namcheon Province (남천주; 南川州; lit. 'South River Province'), appointing the city as the provincial capital. Based on the naming system, the actual name of Han River during this time was likely Namcheon (Nam River) itself or should have the word ending with "cheon" (천; 川) not "gang" (강; 江) nor "su" (수; 水). In addition, "Bukhansan" Jinheung Stele clearly states that Silla had possession of Hanseong (modern day Pyongyang), thus Bukhansan has to be located north of Hanseong. Modern day Pyongyang was not Pyongyang, Taedong River was likely Han River, and Bukhansan was not Bukhansan during the three kingdoms period. Moreover, Pyongyang was a common noun meaning capital used by Goguryeo and Goryeo dynasties, similar to Seoul.