High-quality inverse-opal photonic crystals (see Figure) are formed by TiO2 infiltration and subsequent removal of SiO2 opal templates. Low-temperature atomic layer deposition followed by annealing yields highly conformal infiltrations with extremely smooth surfaces (less than 1 nm root-mean-square roughness) and filling fractions of similar to 88%. Photonic-bandgap properties were determined using UV-vis reflectivity and transmission measurements.