Ogdensburg Armory is a historic National Guard armory building located at Ogdensburg in St. Lawrence County, New York. It was built in 1898 and designed by State architect Isaac G. Perry. It consists of a 2-story, hip-roofed administration building and a large gable-roofed drill shed. It is built of load-bearing, reddish-brown Potsdam sandstone walls built upon a raised, rusticated, light-gray limestone foundation. The main block features 5-, 4-, and 3 1/2-story towers. It was listed on the National Register of Historic Places in 1995.