We present results for the fabrication of a silicon woodpile accelerator structure. The structure was designed to have an accelerating mode at 3.95 ?m, with a high characteristic impedance and an accelerating gradient of 530 MeV/m. The f abrication process uses standard nanofabrication techniques in a layer-by-layer process to produce a three-dimensional photonic crystal with 400 nm features. Reflection spectroscopy measurements reveal a peak spanning from three to five microns, and are s how good agreement with simulations. Show Partial Abstract