Yongsan International Business District: The $25 Billion Redevelopment Reshaping Central Seoul

Why Yongsan Matters More Than Any Other Site in Seoul

Yongsan sits at the geographic and symbolic center of Seoul. The 49.3-hectare former railyard — wedged between the Han River to the south and Namsan Mountain to the north — represents the single largest undeveloped tract of prime urban land in any major Asian capital. For decades, this land served as a military base under Japanese colonial occupation and then as the headquarters compound for United States Forces Korea (USFK). When USFK relocated to Camp Humphreys in Pyeongtaek in 2018, the site became available for civilian development, triggering what has become one of the most ambitious and politically complicated urban redevelopment projects in modern history.

The Yongsan International Business District (YIBD) project, now led by HDC Hyundai Development Company, carries an estimated total investment exceeding $25 billion and envisions transforming the former railyard into a mixed-use district combining corporate headquarters, residential towers, cultural institutions, a central park, and a fully integrated multimodal transport hub. When completed, the district is projected to accommodate 100,000 daily workers, 20,000 residents, and attract an estimated 80,000 visitors daily to its commercial and cultural facilities.

The stakes extend far beyond the project boundary. Yongsan’s redevelopment will reshape property values across central Seoul, redefine the city’s skyline, alter commuter patterns for millions of residents, and serve as a signal to global investors about South Korea’s capacity to execute large-scale urban transformation. It is, by every measure, the defining infrastructure project of Seoul’s 2030 trajectory.

Historical Context: Military Base to Urban Frontier

Understanding Yongsan requires tracing the layers of history compressed into its 49.3 hectares.

The Japanese Imperial Army established its Korean headquarters at Yongsan in 1910, selecting the site for its commanding position between the river and the old city walls. After Korea’s liberation in 1945 and the subsequent Korean War, the United States military inherited the compound. For 65 years, the Yongsan Garrison occupied prime central Seoul real estate — a walled compound of American military buildings, housing, and recreational facilities that functioned as an extraterritorial enclave in the heart of the Korean capital.

The decision to relocate USFK to Pyeongtaek was agreed in 2004 under the Land Partnership Plan and the Yongsan Relocation Plan. The actual move proceeded in phases, with the main headquarters transfer completing in 2018. The return of the land to Korean sovereignty was laden with symbolism — it represented the final removal of a colonial and military legacy from central Seoul.

However, the site also presented enormous challenges. Decades of military use left environmental contamination requiring remediation. The sheer scale of the site demanded urban planning coordination at a level that few municipal governments have successfully managed. And the financial complexity of developing $25 billion worth of mixed-use real estate required navigating Korea’s volatile property markets, regulatory environment, and political dynamics.

The HDC Hyundai Development Plan

HDC Hyundai Development Company emerged as the lead developer after a series of earlier attempts at the site failed. The original YIBD plan, announced in 2006 under Samsung C&T and a consortium of developers, envisioned a 620-meter landmark tower and a total development exceeding $30 billion. That plan collapsed in 2013 when the financial structure unraveled amid the global real estate downturn and regulatory disputes.

HDC Hyundai’s revised plan, formalized through agreements with the Seoul Metropolitan Government and Korea Railroad Corporation (KORAIL) beginning in 2020, takes a phased approach that reflects lessons learned from the earlier failure.

Phase 1: Infrastructure and Transport Hub (2024-2027). The first phase focuses on constructing the underground transport interchange and foundational infrastructure. This includes expanding the existing Yongsan Station — already one of Seoul’s busiest rail terminals handling KTX high-speed rail services — into a fully integrated multimodal hub connecting KTX, Seoul Metro Lines 1, 4, and 6, GTX express rail Line B, and regional bus networks. The underground structure spans approximately 18 hectares and includes three basement levels for transport, parking, and utility infrastructure.

Phase 2: Commercial Core and Landmark Tower (2026-2029). The second phase constructs the primary commercial towers, including a planned 620-meter landmark skyscraper that would become the tallest building in South Korea, surpassing the 555-meter Lotte World Tower in Jamsil. The commercial core is designed to accommodate 15 million square feet of Grade A office space, positioning Yongsan as a competitor to the Gangnam Business District and the Yeouido financial center.

Phase 3: Residential, Cultural, and Park Development (2027-2032). The third phase completes the residential towers (approximately 8,000 units ranging from luxury apartments to workforce housing), cultural facilities including a performing arts center and exhibition hall, and the 12-hectare Yongsan Central Park — designed as the Korean equivalent of New York’s Central Park, positioned between the commercial towers and the Han River.

The Transport Hub: Seoul’s New Multimodal Center

The transport infrastructure beneath the YIBD represents one of the most complex engineering undertakings in Seoul’s history.

Yongsan Station already serves as a critical node in Seoul’s rail network. It is a terminal for KTX services to Mokpo, Yeosu, and other southwestern destinations, handling approximately 60,000 passengers daily. The station also serves Seoul Metro Line 1 (the original north-south subway line) and the Gyeongui-Jungang commuter rail line connecting Seoul to western satellite cities.

The YIBD transport plan expands this capacity dramatically by integrating multiple additional transit lines into a single underground interchange.

GTX Line B Integration. The GTX express rail Line B, currently under construction, will pass through Yongsan, providing direct high-speed connections to Songdo in the south and Uijeongbu in the north. GTX services operate at speeds up to 180 km/h on dedicated deep-bore tunnels, cutting cross-metropolitan commute times by more than 50 percent. The Yongsan GTX station will be located approximately 40 meters below ground level.

Seoul Metro Expansion. The existing Line 1 and connection to Line 4 (via transfer at Seoul Station, one stop north) and Line 6 (at adjacent Hyochanggong station) will be supplemented by improved underground pedestrian connections spanning the entire development site. The plan includes moving walkways linking the transit levels to commercial and residential access points across the 49.3-hectare district.

Bus Rapid Transit Connections. Surface-level BRT stops along the district’s perimeter will connect to dedicated bus lanes running north toward Seoul Station and south toward the Banpo bridge area, maintaining integration with the city’s extensive bus network.

Airport Express. The Airport Railroad Express (AREX) connects through a transfer at Seoul Station, providing a 43-minute direct link to Incheon International Airport. This connectivity is critical for the YIBD’s positioning as an international business district — executives arriving at Incheon can reach Yongsan within an hour door-to-door.

The combined transport hub is designed to handle 400,000 passenger movements daily at full capacity, making it one of the highest-throughput interchanges in Asia. The engineering challenge is compounded by the need to maintain existing rail service throughout construction — KTX trains continue to operate at Yongsan Station while the expanded underground structure is built around the existing tracks.

Engineering and Design Specifications

The YIBD master plan was developed by an international consortium of architecture and engineering firms. The landmark tower design has been attributed to multiple firms at different stages, reflecting the project’s complex history, with the current iteration involving contributions from firms with experience in supertall construction in East Asia and the Middle East.

Geotechnical Challenges. The Yongsan site sits on alluvial deposits from the Han River, requiring deep pile foundations extending 30 to 50 meters to reach bedrock. The proximity to the river raises water table management issues — the three-level underground structure must incorporate continuous dewatering systems and waterproof membrane construction rated for the site’s hydrostatic pressure conditions.

Environmental Remediation. Decades of military use left petroleum hydrocarbon contamination, heavy metals, and other pollutants in the soil. The remediation program, which began in 2019, involves soil excavation and treatment across approximately 15 hectares of the most contaminated areas. The Korean Ministry of Environment supervises the remediation under standards aligned with international best practices. The cost of remediation alone is estimated at 500 billion KRW (approximately $370 million).

Seismic Design. South Korea’s seismic codes were upgraded after the 2016 Gyeongju earthquake (magnitude 5.8) and the 2017 Pohang earthquake (magnitude 5.4) — the two strongest recorded earthquakes in modern Korean history. The YIBD landmark tower and all major structures are designed to exceed the revised Korean Building Code seismic requirements, incorporating base isolation and tuned mass damper systems appropriate for a supertall structure in a moderate seismic zone.

Sustainability Standards. The development targets LEED Neighborhood Development (LEED-ND) Gold certification for the overall district, with individual buildings targeting LEED Platinum or equivalent Korean Green Building Certification (G-SEED) ratings. Energy systems include district heating and cooling supplied by the Seoul District Energy Corporation, rooftop solar arrays, and integration with Seoul’s smart grid infrastructure. The 12-hectare central park is designed as a stormwater management asset, absorbing rainfall and reducing load on the municipal drainage system — a design philosophy informed by the Cheonggyecheon restoration experience.

Economic Projections and Market Impact

The economic impact of the YIBD extends well beyond its construction budget.

Employment. Construction phase employment is projected at 150,000 cumulative job-years over the eight-year build-out. Upon completion, the district’s 15 million square feet of office space is expected to accommodate 100,000 permanent jobs, concentrated in financial services, technology, corporate headquarters, and professional services.

Property Market Effects. The announcement and progressive development of YIBD has already influenced property values in the surrounding Yongsan-gu district. Residential apartment prices in Yongsan-gu increased 42 percent between 2020 and 2025, outpacing the Seoul metropolitan average of 28 percent over the same period. This price appreciation reflects market anticipation of the amenity and connectivity improvements the completed development will deliver.

Competitive Positioning. The YIBD is designed to compete with — and partly supplant — existing business districts in Seoul. The Gangnam Business District, centered on Teheran-ro, has been Seoul’s corporate address of choice since the 1990s. The Yeouido financial district houses the Korea Exchange and major banking headquarters. The YIBD offers what neither can: new-build Grade A office space with direct KTX and GTX connectivity, integrated residential and cultural amenities, and a riverfront park setting.

For international investors, the YIBD represents a direct comparison with projects like Hudson Yards in New York, Canary Wharf in London, and Marina Bay Sands in Singapore — large-scale mixed-use developments that aim to create entirely new urban centers within established megacities.

Political and Regulatory Landscape

The YIBD has been shaped as much by politics as by engineering.

The original 2006 project plan was championed by the Lee Myung-bak administration — the same mayor who delivered the Cheonggyecheon restoration — as part of a broader agenda to modernize Seoul’s physical fabric. The 2013 collapse of that plan resulted from a combination of financial overreach by the developer consortium, regulatory disputes over floor area ratios and height limits, and political opposition from residents concerned about gentrification and displacement.

HDC Hyundai’s revised approach has benefited from a more favorable regulatory environment. The Seoul Metropolitan Government designated the Yongsan area as a Special Planning District in 2021, granting enhanced floor area ratio allowances (up to 1,500 percent in designated zones) and streamlined permitting in exchange for the developer’s commitment to public amenities including the central park, affordable housing allocations, and cultural facilities.

The national government’s role is also significant. The Ministry of Land, Infrastructure, and Transport oversees the KORAIL land disposition, as KORAIL (a state-owned enterprise) owns substantial portions of the site as former railyard land. The terms of the land sale and leaseback arrangements between KORAIL and HDC Hyundai have been subject to National Assembly scrutiny, reflecting the political sensitivity of transferring prime public land to private developers.

The environmental remediation timeline adds another layer of regulatory complexity. The Ministry of Environment must certify land parcels as remediated before construction can proceed, creating a sequential dependency that constrains the overall project schedule.

Comparisons with Global Mega-Projects

The YIBD invites comparison with the largest urban redevelopment projects worldwide.

The YIBD’s 49.3-hectare footprint exceeds Hudson Yards by more than four times, making it one of the largest urban mixed-use developments currently under construction globally. The $25 billion investment figure is comparable to Hudson Yards, though the significantly larger site area at Yongsan means the per-hectare development intensity is lower, accommodating the 12-hectare central park.

The transport integration at Yongsan is arguably more sophisticated than any of these comparisons. Hudson Yards sits atop an extended platform over active rail lines but is served by a single subway line and no intercity rail. Canary Wharf added the Jubilee Line extension and later the Elizabeth Line (Crossrail). The YIBD integrates KTX high-speed rail, GTX express commuter rail, two metro lines, AREX airport service, and BRT in a single interchange — a level of multimodal connectivity that few projects anywhere in the world can match.

The Yongsan National Park Component

A critical and often underappreciated element of the YIBD is the planned Yongsan National Park. President Yoon Suk-yeol announced plans in 2023 to develop the former USFK garrison — distinct from but adjacent to the YIBD railyard — into a national park four times the size of New York’s Central Park. The 243-hectare park would incorporate the former military base land, connecting to the YIBD’s 12-hectare central park to create a continuous green corridor from Namsan Mountain to the Han River.

This parkland integration transforms the YIBD from a standalone commercial development into the commercial edge of Seoul’s largest urban park. The adjacency to 243 hectares of parkland dramatically increases the amenity value of YIBD residential and commercial properties — an effect well-documented in studies of Central Park’s impact on Manhattan property values.

The park plan also addresses environmental justice concerns. Unlike the YIBD commercial district, which will primarily serve corporate tenants and affluent residents, the national park will be freely accessible public space. The combination of private development and public parkland represents an attempt to balance the economic exploitation of the site with equitable access to its environmental amenities.

Risks and Challenges Through 2030

The YIBD faces several material risks that could affect its timeline, budget, and ultimate form.

Financial Risk. A $25 billion development spanning eight or more years is exposed to interest rate cycles, property market corrections, and tenant demand fluctuations. South Korea’s property market experienced significant turbulence in 2022-2023, with housing prices declining 15 to 20 percent in some Seoul districts before recovering. A sustained downturn during the YIBD’s critical Phase 2 commercial leasing period could force design revisions, delayed construction, or reduced scope.

Environmental Remediation Delays. The contamination remediation timeline is inherently uncertain. Unexpected contamination discoveries — common on former military sites — could delay land certification and cascade through the construction schedule.

Political Continuity. Korean presidents serve single five-year terms, and mayoral administrations turn over every four years. The YIBD’s 2024-2032 timeline spans at least two presidential administrations and potentially three mayoral terms. Each transition carries the risk of policy shifts, regulatory reinterpretation, or changed political priorities.

Construction Complexity. Building a 620-meter supertall tower, three-level underground transport hub, and 8,000-unit residential complex simultaneously on a remediated former military site adjacent to active rail operations represents an engineering challenge of extreme complexity. South Korea has demonstrated the construction capacity to execute such projects — the Lotte World Tower was completed successfully — but the Yongsan site’s layered constraints exceed any single precedent.

What Yongsan Means for Seoul’s 2030 Vision

The YIBD is not merely an infrastructure project. It is a test of whether Seoul can execute 21st-century urban development at a scale and quality that matches its economic ambitions.

The city that built the Seoul Metro system — 23 lines, 624 stations, 6.6 million daily passengers — in four decades, that restored Cheonggyecheon in 27 months, that operates Incheon Airport at the highest service quality in the world, must now demonstrate that it can build a new urban center from scratch on the most politically and environmentally complex site in the country.

Success at Yongsan would confirm Seoul’s position among the small number of cities — Singapore, Dubai, Shanghai — capable of delivering mega-scale urban transformation. Failure or chronic delay would signal that even South Korea’s formidable construction and planning apparatus has limits.

The project’s integration of transport infrastructure, commercial development, residential housing, cultural facilities, and parkland into a single master-planned district represents the fullest expression of Seoul’s urban planning philosophy: that infrastructure is not a passive utility but an active instrument of economic development, environmental strategy, and civic identity. By 2030, the early phases of the YIBD will reveal whether that philosophy can deliver on its most ambitious promise yet.