D W Griffith's major film was the notorious "The Birth of a Nation" (1915) noted for being the first major American feature film. Due to its racist content it's not a film which can ever be recommended to see.
Much more palatable was his second major film "Intolerance" (1916). It's nearly 3 hours long and consists of 4 stories from diferent historic eras. It's a very ambitious large scale film. Although very dated, for film buffs it's a must.