Ancient Egyptian hieroglyphs at the Temple of Seti I in Abydos depict a helicopter, submarine, and other modern machines: proof of ancient advanced technology or alien contact.

At the Temple of Seti I in Abydos, weathered stone carvings appear at a glance to show a helicopter, a submarine, and other modern vehicles, which ancient-astronaut theorists point to as evidence ancient Egyptians had advanced technology or alien contact. No credible Egyptologist has ever endorsed that reading; the accepted explanation is that this is a palimpsest. When Ramesses II took the throne after his father Seti I, plaster was used to carve Ramesses's own royal titles directly over Seti's original inscription in the same stone space, a well-documented practice when a new pharaoh asserted his line over a predecessor's.

Over three thousand years the plaster filler crumbled away, leaving two overlapping sets of hieroglyphs from two different reigns whose combined outlines happen to resemble modern machinery. This is a known, named archaeological process (a palimpsest relief) with a specific, datable cause. Ramesses II's re-inscription at Abydos is documented independently of this controversy, so what's left isn't an unsolved mystery.