Located in Gangnam, at the boundary where the gridded new town built on reclaimed land from the Han River floodplain meets the older organic urban fabric, Urban Horizon negotiates the tension between imposed order and accumulated density. Departing from the conventional closed model of Korean schools, the design opens itself to the city. A linear structure defines the site’s edge, linking the commercial district with the athletic field and main school building. Bleachers facing the field reinforce visual continuity between interior and exterior spaces. At the corner where the diagonal axis of Garosu-gil intersects the site, an entry sequence unfolds from the ground plane to a rooftop garden. Planted with native grasses and wildflowers, this elevated landscape functions both as an ecological classroom and as a shared green refuge. On the opposite corner, a vehicular entrance and roof stair also extend connections to the other diagonal streets. Originally conceived as an annex to provide additional classrooms, the project was designed to evolve into a community facility as student enrollment declined. With a flexible steel-frame system, it accommodates both school functions and public programs, anticipating future reconfiguration. Ultimately, the design dissolves boundaries between architecture and landscape, creating a continuous gesture from ground to roof and redefining the school as a new urban horizon within the city.