Metallosupramolecular assemblies of the general formula M2nLn can adopt prismatic or cage‐like structures. The factors controlling the aggregation number n and the geometry of the final assembly are still not fully understood. Here, we describe the synthesis and the structural characterization of PtII8L4 complexes, which adopt tetragonal prismatic structures. The bridging ligand L features four pyridyl groups and an inert FeII clathrochelate complex at its core. Furthermore, the ligand has three phenanthrene groups, which are attached to the FeII complex in a divergent fashion. These polyaromatic side groups control the self‐assembly process by promoting the formation of a structure, which allows for an energetically favorable packing of the aromatic groups. Replacing the phenanthrene groups on the ligand by aliphatic n‐butyl groups results in a complete change of geometry: instead of tetragonal prisms, PtII8L4 complexes with cage‐like structures are observed.