Seoul's Hidden War: The Secret Battle for Hangang

Lucas: If you walk through downtown Seoul today, near the Gyeongbokgung Palace, you might not realize that beneath your feet lies one of the city’s most dramatic transformations. For centuries, the Cheonggyecheon Stream wound its way through the heart of the capital, serving as both a sewage ditch and a lifeline for merchants and fishermen alike. Luna: I’ve seen pictures of it, but I never really thought about what it was before the cars took over. Lucas: It’s easy to forget because, for about forty years, it didn’t exist as a natural feature at all. By the late 1960s, the stream had become an open sewer, choked with industrial waste and home to thousands of informal settlers living in shanties along its banks. It was a symbol of the chaos that accompanied rapid urbanization. Luna: So they just decided to bury it? Lucas: Exactly. In 1967, the city began covering the stream with earth, and by 1971, they paved over it entirely to build an elevated highway. This was the height of Park Chung-hee’s industrial drive, where efficiency and speed were paramount. The goal was simple: get cars moving faster to fuel the economy, even if it meant losing the waterway forever. Luna: That sounds incredibly destructive for the environment. Lucas: It was, but at the time, it was seen as progress. The elevated highway, known as the Cheonggye Elevated Expressway, became a vital artery for Seoul’s booming traffic. Yet, by the 1990s, the structure was crumbling, air quality was plummeting, and the neighborhood around it had fallen into decay. The very solution to congestion had created a new kind of urban blight. Luna: Did anyone try to bring it back sooner? Lucas: There were whispers of restoration in the late nineties, but it wasn’t until 2002 that the idea gained real traction. A young politician named Oh Se-hoon ran for mayor on a platform that included digging up the stream. It was a radical concept—removing a major highway to plant a park instead—and many experts called it impossible or economically foolish. Luna: He actually did it then? Lucas: He did. Between 2003 and 2005, crews demolished the six-lane elevated expressway and uncovered the stone channels beneath. They spent months cleaning the bedrock and restoring the flow of water, creating a twenty-two-kilometer linear park that connected the old royal palace to the modern business district. It was a massive engineering feat, costing nearly three hundred million dollars. Luna: Three hundred million dollars just to dig up a road? Lucas: To the critics, yes. But the results were immediate and staggering. Traffic actually improved because people shifted to public transit, property values in the surrounding area skyrocketed, and the city saw a significant drop in local temperatures due to the cooling effect of the water. It became a model for sustainable urban planning worldwide. Luna: That’s a pretty huge turnaround from the pollution days. Lucas: It really is. But we can’t ignore the human cost of that original paving in the seventies. Thousands of families who lived along the Cheonggyecheon were displaced without adequate compensation. Many ended up in cramped apartments on the city’s outskirts, their livelihoods as street vendors or small-scale artisans wiped out by the need for concrete. Luna: It feels like progress often leaves people behind. Lucas: Always. And when the stream was restored, those original residents weren’t necessarily the ones benefiting from the new upscale cafes and boutiques. It highlights a tension in modern Korean history: the trade-off between national economic power and individual well-being. The Miracles on the Han River were miraculous for the state, but messy for the people. Luna: Did the government help those displaced families later? Lucas: Some received housing, but the social fabric of those riverside communities was shattered. Today, you can still find traces of that history in oral accounts from elderly residents who remember when the water flowed clear and the sound of carpenters working echoed off the stream banks. It’s a ghostly reminder of what was lost. Luna: I can imagine how loud the highway must have been compared to the water. Lucas: The noise levels under the expressway were recorded at over eighty decibels, essentially constant traffic roar. Now, with the stream restored, visitors can hear the gentle rush of water and birdsong. It’s a sensory shift that defines the new Seoul experience. Luna: It sounds almost poetic, changing from concrete back to water. Lucas: In a way, it is. And it ties into a broader theme of how South Korea has redefined its identity. Moving from a war-torn nation focused on survival to a global leader in design and sustainability. The Cheonggyecheon project signaled that maturity. Luna: A mature approach to city building. Lucas: Precisely. Before we dive deeper into the specific engineering challenges they faced during the excavation, I want to take a brief moment to acknowledge the listeners who keep this network running. If you've been stepping into history with us episode by episode, your support ensures we can continue producing these deep dives without ads cluttering our conversations. You can find us at buy me a coffee dot com slash fexingo. It’s a small gesture that makes a big difference in keeping these stories accessible and ad-free. Luna: Thanks for making sure the show stays clean and focused. Lucas: Back to the stream. The excavation itself was fraught with technical difficulties. Archaeologists discovered layers of history beneath the concrete, including remnants of Joseon-era bridges and even older artifacts dating back to the Three Kingdoms period. Luna: They found old bridges right there? Lucas: Yes. One of the most significant finds was the Myeongbo Bridge, a historic stone bridge that had been buried for decades. Restoring it required meticulous work to ensure it matched its original appearance while supporting modern foot traffic. It served as a tangible link between the past and present. Luna: It must have been surreal for workers to uncover that. Lucas: Absolutely. And beyond the archaeology, they had to manage water flow from the Hangang River. Pumping millions of gallons of water daily to maintain the stream’s level was a logistical nightmare. They installed advanced pumping stations to ensure the water remained clean and circulating, preventing stagnation. Luna: Keeping the water fresh in such an urban setting. Lucas: Exactly. And this led to another unexpected benefit: biodiversity. Within months of opening, dozens of bird species returned, and fish populations stabilized. It proved that nature could reclaim space even in the densest parts of a megacity. Luna: That’s incredible resilience from nature. Lucas: It is. But the project also sparked debates about gentrification. As the area became more attractive, rents rose, pushing out long-time small businesses. Critics argued that it was just another form of exclusionary urban renewal. Luna: So the cycle of displacement continued, just differently. Lucas: In many ways, yes. The challenge for Seoul now is balancing preservation with affordability. How do you honor the memory of those who lived along the stream while ensuring the space remains accessible to everyone, not just the wealthy. Luna: It’s a complex legacy. Lucas: It is. But standing by the water today, you can feel the weight of that history. From the darkness of the covered era to the light of the restored park, it mirrors South Korea’s own journey. Luna: A journey from shadow to light. Lucas: I think so. And it leaves us wondering what other hidden histories lie beneath our cities, waiting to be uncovered. Luna: Probably more than we realize. Lucas: Indeed. Perhaps next time we’ll look at how other Asian capitals are handling their own forgotten waterways. Luna: I’d love to hear that. Lucas: Until then, keep listening, and keep questioning the ground you walk on.