There is absolutely no doubt in my mind that the finest documentary series ever produced was the 1973, 26 Episode Thames Television series The World at War. I have hunted for it everywhere hoping to find it and finally have.
All 26 episodes are available free online at Cosmo Learning. They have also made available the 5 special presentations, The Making of World at War, Secretary to Hitler, Hitler's Germany, The Final Solution, and Peace after War as well as three previously unreleased interviews. The 26 episodes are playable in 89 segments.
This is what television could have been, what it should have been. It is also what documentaries should, presented as history without the propaganda and bias journalism that pervades television today.
You will have no finer viewing and historical experience than this series. Hunker up to your computer screen and enjoy.