Two-dimensional photonic band-structure effects have been observed in the visible and near-uv regions, between 350 and 800 nm. These effects appear in all-solid-state arrays of glass cylinders in a glass matrix. The arrays have center-to-center nearest-neighbor separations between 0.188 and 0.278 μm, perfect long-range order, and low refractive index contrast. For light propagating perpendicular to the cylinder axes, very narrow attenuations appear in the transmission spectra as a result of the photonic band structure. The positions of these attenuations are determined by the periodicity, composition, and symmetry of the arrays.