N-ground or multi-ground (Superground & Underground) concept applied to Seoul, call us to a new qualitative development that responds to the possibility to superimpose a new dense floor in the old infrastructures. A new ReCitying Topos on, inside, in, where and through which to develop new/old programs, uses and activities of life and relationship. The singularity of Seoul is the capacity for the city to combine and manage all the new global urban paradigmatic challenges. Seoul new qualitative development responds does not intend to "continue" or "recreate" the traditional city. Nor impose or positionate, transforming it, built machines or objects but superimpose a new dense floor (container and articulator at the same time) in the old obsolete infrastructures, that becomes a new Re-Citying. The old infrastructures are revealed as the ideal spaces to support these new floors, real and virtual at time. Projects: AZPML, NO.MAD, Chanjoong Kim, Eun Young Yi, Studio Fuksas, Alejandro Haiek, Mass Studies, NL Architects, IROJE, Francis Soler, It's, Michel Desvigne, MVRDV, Dominique Perrault, Go-Up Architects, Topotek 1, Atelier Bow-Wow, Charles Waldheim, among others Published by Seoul Metropolitan Government in English & Korean