Like many things in Korea, Seoul would undergo great changes after late President Park Chung-hee took power in 1961. In 1962, the government enacted the Special Act for the Administration of Seoul Special City. With it, the city was placed under the direct administration of the Office of the Prime Minister. Meanwhile, the Mayor of Seoul was promoted to the rank of minister. In 1963, the city was greatly expanded, this time to 593.75 square km. Under this expansion, some seven myeon and 54 ri were created out of territory originally belonging to Yangju, Gwangju, Siheung, Gimpo and Bucheon counties. This territory would later become Seoul`s (now) affluent Gangnam (South of the River) region.

In 1973, the city was further enlarged to 605.33 square km. The city grew to 11 gu with the addition of Dobong-gu and Gwanak-gu. In 1975, Gangnam-gu was created, in 1977, Gangseo-gu, in 1979 Eunpyeong-gu and Gangdong-gu, and in 1980 Dongjak-gu and Guro-gu. Some gu were later newly created out of others. In 1988, Jungnang-gu was split from Dongdaemun-gu, Nowon-gu was split from Dobong-gu, Yancheon-gu was split from Gangseo-gu, Seocho-gu was split from Gangnam-gu, and Songpa-gu from Gangdong-gu.

In 1994, the city celebrated 600 years as the national capital.

In 1995, Gangbuk-gu was separated from Dobong-gu, Seongdong-gu was separated from Gwangjin-gu and Geumcheon-gu was taken from Guro-gu. Since 1973, the area of Seoul has remained fixed; the expansion of gu has been to more effectively deal with the growing population. In the 1970s, as the "Miracle on the Han" grew more and more apparent, the city’s character began to change dramatically. South of the Han River, in the Gangnam district, row upon row of high-rise apartment buildings sprout up in what would become some of Seoul’s most affluent residential districts. Once nothing but farmland, the area south of the river grew and grew in population. Today, the Gangnam and Gangbuk regions are roughly the same in population.

The expansion of the population, of course, led to several problems, not the least of which was pollution. Green belts to control the size of the city were established in 1971. Affluence has led to a shift in values, and recently, there has been great efforts made to make the capital a more ecologically friendly and citizen-oriented city. The restoration of the Cheonggyecheon Stream, covered over during the Park Chung-hee period, is just one example of this trend. Efforts have also been made to control the increasing population, including the moving of administrative buildings away from Seoul to outlying areas and the construction of so-called "satellite cities" to lure people away from Seoul to other communities nearby.

Archaeological evidence suggests that there have been collective settlements along the Han River since about 4,000 B.C. The prehistoric remains unearthed in Amsa-dong, Gangdong-gu date back to the Neolithic Age (about 7,000-3,000 years ago). Settlements formed tribal alliances as metalworking was introduced to Korea from China.

In 108 BC, the Chinese defeated the old Korean kingdom of Gojoseon, and four Chinese commanders were established on the Korean Peninsula. The area that is now Seoul was originally under the Zhenfan Commandery. Korean resistance eventually forced the Chinese out, and the area became part of the Korean state of Mahan.

From 18 BC, the kingdom of Baekje began to expand from the area that is currently Seoul. Baekje was founded in a place called Habuk Wiryeseong, which is believed to be in what is now Seoul’s Mia-dong, Dobong-gu.

Soon after Korea saw the rise of two other powerful kingdoms, Goguryeo in the north and Silla in the southeast. The Seoul area became a major strategic spot and a major source of conflict as the three kingdoms frequently clashed to take possession of the vital area.

In 392, King Gwanggaeto the Great of the Goguryeo kingdom attacked Baekje and took temporary possession of Seoul. In 475, King Jangsu attacked Baekje again, establishing a town in the Seoul area called Bukhansanju. The old town of Wiryeseong was renamed Nampyeongyang ("South Pyeongyang").

Afterwards, Baekje experienced a recovery, and in alliance with Silla (which was itching to expand its territory), it ousted Goguryeo out of the Han River valley in 551. Silla, however, took control of the area. The alliance with Baekje broke down and a war between the two states broke out. The Baekje king was killed in battle, and King Jinheung of Silla took complete control of the vital region.

When the Silla kingdom finally unified the Korean Peninsula, it included the Seoul area in the province of Hansanju, one of nine set up by the victorious kingdom. Queen Gyeongdeok to Hanju later renamed the province, while the Seoul area was called Hanyang County. The name "Hanyang" would much later come to refer to the city, and lives on in the name of Hanyang University, one of Seoul’s best centers of higher learning.

With the opening of Korea in 1876, modern facilities began to appear in including hospitals, schools, churches, newspapers and the like. In 1898, a streetcar service opened between Seodaemun and Hongneung. In 1895, the city was renamed Hanseong-gun, and reorganized into five bu and five seo. The following year, the city was renamed Hanseong-bu. In 1899, rail service opened linking the city with the port of Incheon. Phones were installed for the first time. In 1900, the first bridge over the Hangang River was completed.

The forced annexation of Korea by the Japanese in 1910, however, saw the city demoted and placed under the administration of Gyeonggi-do. It was also renamed Gyeongseong-bu. The city was divided into five bu and eight myeon. The five bu, located inside the city gates, were the North, South, East, West and Central bu, while the five myeon, all located outside the gates, were Yongsan, Seogang, Sungsin, Dumo, Inchang, Eunpyeong, Yeonhui and Hanji.

In 1914, this system was abandoned, and certain areas of the city’s administrative district greatly expanded.

In 1905, the city had a population of some 250,000 people. With increases in the Korean population of the city and the influx of Japanese settlers, by 1936, the population had soared to 730,000, and the city’s area expanded to 133.94 square km. Areas of surrounding cities were incorporated into the city, and administrative offices were built in Yongsan, Dongbu and Yeongdeungpo.

The Jongno, Namdaemunno and Taepyeongno areas became a prosperous downtown area. At the same time, the areas around Cheongnyangni, Mapo, Donam-dong, Yeongcheon, Yeongdeungpo and other areas around streetcar lines and stations became urbanized.

On the north side of Mt. Namsan, Japanese residential districts were established, filled with Japanese-style wooden homes. In 1943, a new administrative system was adopted, the city being divided into seven gu. In 1944, the city was enlarged once again, this time adding an eighth gu, Mapo-gu.

When Korea was finally liberated following the defeat of Imperial Japan in World War II, the capital was renamed Seoul. Unlike other cities in Korea, the city's name is not a Sino-Korean derivation, but rather an indigenous word meaning "capital." The term is said to have been in use since the Silla period.

Having been placed under the administration of Gyeonggi-do by the Japanese, the city was once again separated from the surrounding province and declared the Special Free City of Seoul and placed under the direct administration of the central government, something akin to the District of Columbia in the United States. In addition, Japanese-style administrative district names such as "jeong" and "ga" were changed to the more Korean "dong" and "ro."

On August 15, 1949, exactly one year following the foundation of the Republic of Korea, the city was renamed the Special City of Seoul. With the population on the increase, parts of several surrounding counties were incorporated into the city, boosting the size of the city from 136.06 square kilometers to 268.35 square kilometers. A ninth gu, Seongbuk-gu, was created, and the population topped 1.4 million.

With the outbreak of the Korean War in 1950, early efforts to develop Seoul went to waste, and large parts of the city were laid to waste. During the course of the war, the city changed hands a total of four times, three of those within a six-month period. During the war, the national capital was forced to move to Busan in the face of advancing enemy forces, although it would return to Seoul permanently on August 1, 1953.

Following the war, efforts were begun anew to rebuild the city from the ashes, but these would prove slow and painful. Much of the city lay in ruins, and resources were scarce in a country poor after 35 years of colonial rule and three years of bitter war. Of primary importance was the rebuilding of housing in order to move people from wartime refugee camps.

Despite the wartime damage, Seoul’s population continued to grow. At the same time, new administrative bodies were created in order to handle the city’s burgeoning population and growing role as a national capital.

In 918, the Silla Kingdom fell and was replaced by the Goryeo Kingdom, which succeeded in unifying the Korean Peninsula from the South Sea to the Yalu River. The Han River valley, as a major transportation route and a region of agricultural and commercial wealth, was of particular interest to the new kingdom.

Under King Seongjong, Seoul became a very important administrative district, and its political influence grew.In 1067, when the kingdom designated three sub-capitals, Seoul was designated the "Southern Capital," or Namgyeong. With the promotion of Seoul to the southern capital, the city assumed an important place in the regional administrative system.

At the time, Seoul stretched from Mt. Naksan to Mt. Ansan (east to west) and from Mt. Bukhan to Yongsan from north to south. This was a historical pivotal point in the development of Seoul. For the first time, palaces were built in the city, and with subjects in neighboring territories moving to the town, it took on the shape of a city.

Later, King Sukjong built a palace where the current Cheong Wa Dae presidential palace now stands. He planned to move the kingdom`s capital to the site, but the plan came to naught with Sukjong`s death. With the Mongol invasion of 1231, the Goryeo capital (present day Gaeseong) was moved temporarily to Ganghwa Island. The Mongolian army then occupied Seoul. Under the influence of Yuan China, the three-capital system was done away with, and the city was renamed Hanyang-bu.

When the anti-Yuan King Gongmin assumed the throne, he attempted to resurrect the three-capital system. Talk began of moving the capital to the Hanyang. This talk heightened during the reign of King Uwang, and for a short time starting in September of 1382, the capital was moved to the city.

In July of 1392, Gen. Yi Seong-gye founded his own dynasty, which was named the Joseon Kingdom. Following the advice of retainers like the Buddhist monk Muhak, the new king designated Hanyang as the capital of his kingdom in 1393. Construction began on the Jongmyo and Sajik shrines as well as palace facilities, and in 1394, the capital was officially moved. The following year, the city was renamed Hanseong-bu. Construction on the Gyeongbokgung palace was completed. In 1396, the city`s administrative districts were set and the city`s walls and gates completed. Some 18 km of walls were built, ringing the ridges of Mt. Bugaksan, Mt. Inwang-san, Mt. Namsan and Mt. Naksan.

City planning was complete by 1405. City planning during the Joseon era was carefully done, with the palaces built underneath Mt. Bugak and the roads centered on Gwanghwamun Gate, Namdaemun Gate and Jongno. Amazingly, Seoul’s current outlay holds pretty much true to this original plan.

Under King Yeongjo, who reigned during the mid-18th century, the city flourished. Trade routes along the Han River grew more traveled, and the city began to take on the shape of a modern commercial center as linkages were made with merchants in Gyeonggi and Gangwon provinces. In 1428, the city’s population was 103,328 people, 110,000 if the population outside the walls is included. For some 200 years following, the city maintained a population of 200,000. During the Japanese invasions of 1592 and the Manchu invasion of 1624, the city suffered great human and property losses.

For some 500 years, the city was broadly divided into "the area inside the walls" and "the area outside the walls." The area inside the walls were further divided into 5 bu and 52 bang, which roughly correspond to today’s gu and dong.