A novel approach to constructing hierarchical superstructures made up of porphyrin box (PB), a porous organic cage, is presented. We have previously reported a series of rationally designed porous organic cages, the porphyrin boxes (PBs), which consist of square-shaped porphyrin and triangular-shaped triamine subunits. The truncated cubic-shaped geometry and six porphyrin faces of the PBs prompted us to explore metallated PBs as pre-made and atomically-precise organic building units to construct hierarchical superstructures linked by properly designed ditopic bridging ligands. Using this approach, we obtained two- and three-dimensional PB-based superstructures (PSS), and found that there is an optimum range of the linker length for the construction of PSSs. The hierarchical structures were confirmed by single-crystal X-ray diffraction analysis. The PSSs have a protein-like large unit cell (>40 Å) with a spacious void volume (62%) and larger extrinsic surface area compared to that of the parent PBs, which can be exploited for selective encapsulation of guest molecules, interior functionalization, catalysis etc. As a proof-of-concept, we demonstrated that singlet oxygen-induced synthesis of a natural product, juglone, is more efficiently catalyzed in presence of PSS-1 than by its constituent component Zn-PB.^1,2 References ¹Kim, Y.; Koo, J.; Hwang, I.-C.; Mukhopadhyay, R. D.; Hong, S.; Yoo, J.; Dar, A. A.; Kim, I.; Moon, D.; Shin, T. J.; Ko, Y. H.; Kim, K. J. Am.Chem. Soc. 2018, 140, 14547-14551. ²Mukhopadhyay, R. D.;§ Kim, Y.;§ Koo, J.;§ Kim, K. Acc. Chem. Res. 2018, 51, 2730-2738.