Seo District is a gu ("district") of Daejeon, South Korea. Daejeon Metropolitan City Hall is also located there. This is a self-governing district located in the southwestern part of Daejeon Metropolitan City. It serves as the central hub of the city, hosting several major developments such as Dunsan New Town, Gwanjeo District, and Doan New Town. With a population of approximately 470,000, it is the most populous district in Daejeon, accounting for about one-third of the city's total population.