Pictured is an ancient Egyptian glyph from Abydos, that some have interpreted as depicting a helicopter. In a 1999 article(1) from Enterprise Mission, Richard C. Hoagland characterizes the glyph as "memorializing information" by the Egyptians of a high-tech civilization previous to theirs. Another take on the Abydos glyphs is posted in the article Pharaoh's Helicopter?(2)
1. http://www.enterprisemission.com/tombsweb6.html
2. http://www.catchpenny.org/abydos.html