These Fritz Lang films from 1924 follow the famous stories of Siegfried, beginning with the sword that he forged to slay the dragon.
The actor playing King Etzel in Kriemhilds Rache probably goes down in history as one of the most exciting actors of the silent film era. Rudolf Klein-Rogge, who had been married to screenwriter Thea von Harbou until 1921, played evil geniuses very well. He played Dr. Mabuse in that series of films, was in Spies, and was even Erfinder Rotwang in Metropolis. Unfortunately Goebbels was not happy with him, so his career more or less came to an end during the war.
Part of the story of Siegfried is how bathing the the dragon blood affects his life. This is also shows. For anyone concerned with seeing a nude man from behind, this scene is approximately 23 minutes into Siegfried and lasts perhaps 30 seconds (it was a big enough deal to the actor, Paul Richter, that he refused to do it, and Rudolf Klein-Rogge became a body double for him). Kriemhilds Rache has more nudity to look out for in classroom settings. When she goes to meet the Huns, there are many nude and partially nude people. This begins around 33 minutes in and lasts for several minutes off and on. Another set of this begins around 55 minutes in, 1 hour and 5 minutes, and finally 1 hour 31 minutes.
Note: Siegfried is actually 2 hours and 20 minutes (not the 90 minutes advertised in IMDB). Kriemhilds Rache is actually 2 hours and 27 minutes.