Hornell Armory is a historic National Guard armory building located at Hornell in Steuben County, New York. It is a brick and stone castle-like structure built in 1894. It was designed by architect Isaac G. Perry. The three-story main structure has a four-story round corner tower. Attached to the main structure are an additional pair of two-story corner towers. Extending from the main structure is a long two-story wing with a gable roof and corner stair tower.