The Flatiron Building was originally known as the Fuller Building. It's a triangular 22 story, steel-framed structure located at 175 Fifth Avenue in Manhattan, NYC, and it's a building that is hard to miss when you're in that area in New York. Upon completion in 1902, the Flatiron one of the tallest buildings in the city. The building was designated a New York City landmark in 1966 and was added to the National Register of Historic Places in 1979. It was designated a National Historic Landmark in 1989.