In this work, we report the formation of superstructures assembled from organic tubular crystals mediated by metal-coordination chemistry. This template-free process involves the crystallization of molecules into crystals having a rectangular and uniform morphology, which then go on to fuse together into multibranched superstructures. The initially hollow and organic crystals are obtained under solvothermal conditions in the presence of a copper salt, whereas the superstructures are subsequently formed by aging the reaction mixture at room temperature. The mild thermodynamic conditions and the favorable kinetics of this unique self-assembly process allowed us to ex-situ monitor the superstructure formation by electron microscopy, highlighting a pivotal and unusual role for copper ions in their formation and stabilization.