Seti I was a pharaoh in the 19th dynasty of Egypt, the son of Ramesses I and father of Ramesses II. His temple is located in what is known today as the sacred city of Abydos, Egypt, which is considered one of the most important archaeological sites in Egypt. The walls are decorated with a host of inscrutable hieroglyphics, including a catalog list of the cartouches (symbols or seals) of every Egyptian pharaoh before him.
What grabs the attention of modern onlookers, however, is the uncanny resemblance between some of the symbols on the walls and modern inventions, including helicopters, submarines, and zeppelins:
This oddity has fed rumors of ancient aliens or time-travelers on the usual sites. However, there are perfectly mundane explanations for these figures, in that they aren't really detailed to begin with, have decayed several centuries, and could be depicting perfectly ordinary everyday objects of the time, or perhaps, like the sketchbooks of Leonardo da Vinci, been a particularly bright attempt at imaging the future. After all, our modern flying machines do indeed resemble natural flying creatures, and if any preindustrial artist would have been asked to imagine a man-built flying machine in the future, very few could argue against designing something that looks fairly like what devices we have today. You wouldn't imagine that an airplane shaped like a fish or turtle could fly, could you?
The complete diagram of the temple:
Abydos became a popular necropolis in ancient Egypt, containing many temples and burial sites devoted to Egyptian royalty. This has also led to the general area becoming a focus for all sorts of cult and superstitious activity throughout the decades. More research into this intriguing historical area here.