Complex sentence: Before his death Engleitner was the world's oldest known male concentration camp survivor (held in Buchenwald, Niederhagen and Ravensbrück), and the oldest male Austrian.
Split into simpler sentences: Before his death, Engleitner was the oldest survivor of the concentration camps Buchenwald, Niederhagen and Ravensbrück. He was the world's oldest known male concentration camp survivor, and the oldest male Austrian.