For Koreans, who must endure scorching summers and freezing winters, apartment complexes have long served as the ultimate symbol of housing efficiency as well as their most prized financial assets. Beyond property value and redevelopment, these concrete complexes also preserve residents' memories, neighborhood bonds and urban nature. Director Lee Sung-min’s documentary film, "Green Concrete," explores this tension by capturing the demolition of a massive residential complex in southern Seoul's Gaepo-dong. Over seven years from 2017, the 103-minute documentary shows both the changing cityscape and the fate of the trees planted there for decades. Lee, who grew up in the complex, initially returned to document the space before its disappearance. What started as a personal recording effort soon grew into a collective project gathering former residents to share old photos and memories. Through these shared stories, the film portrays the vanishing apartment complex as one of the few remaining green spots in a concrete-dominated landscape. Rather than choosing a side in the redevelopment debate