ROME — The Venice Film Festival is celebrating the 80th year since its first edition with a retro of vintage titles from its archives, some of which are the only copies of pluriprized pics.Among these is the single surviving print of Emmy Award-winning PBS docu “Free at Last,” which chronicles Martin Luther King’s 1968 march on Washington and became an important document after his assassination. “Free,” which was directed in cinema verite style by Gregory Shuker, James Desmond and Nicholas Proferes, also took a Venice nod. All titles in the Lido’s 10-pic retro were chosen based on their rarity. All are being restored for the occasion under the supervision of Venice topper Alberto Barbera. After unspooling on the Lido, they will become available for future commercial or cultural use. Other titles include Russian helmer Yuli Raizman’s 1936 “The Last Night,” about the sudden arrival of Communism in Russia; Gallic director Jean Delannoy’s 1950 spirituality-themed “God Needs Men,” and Carlos Saura’s 1968 road movie “Stress Is Three,” starring Geraldine Chaplin. The 69th edition of the Venice fest, which started in 1932, but was since interrupted by war and other upheavals, will run Aug. 29-Sept. 8.