Brosemer Brewery, also known as the Seaway Supply Building, is a historic brewery located at Oswego in Oswego County, New York. It was built in 1888 and is a four story building measuring approximately 50 feet wide and 126 feet deep. It is a heavy timber post and beam and brick masonry structure on a limestone foundation. It ceased use as a brewery in the 1920s, after which it housed manufacturing and warehousing companies. It was listed on the National Register of Historic Places in 2010.