Large-area one-dimensional periodic metallic structures were fabricated on a waveguide layer with interference lithography and dry etching. As narrow as 115-nm gold nanowires were obtained with a period of 395 nm, covering a homogeneous area as large as 5 × 5 mm2. Extinction measurements demonstrate the strong coupling between waveguide mode and gold-particle plasmon resonance. We demonstrate good agreement with a scattering-matrix theory. The dispersion of the metallic photonic crystals was obtained by angle-resolved measurements. This method represents a simple and low-cost way to fabricate large-area metallic photonic crystals.