Colloidal crystals are ordered arrays of particles in the nanometre-to-micrometre size range. Useful microstructured materials can be created by replicating colloidal crystals in a durable matrix that preserves their key feature of long-range periodic structure. For example, colloidal crystals have been used to fabricate structures from inorganic oxides^,,,,, polymers^,, diamond and glassy carbon, and semiconductor quantum dots, and some structures have photonic properties^,, or are patterned on different hierarchical length scales. By using colloidal crystals as templates, we have synthesized a new class of metallic materials with long-range nano-scale ordering and hierarchical porosity.