Do you know when the first flying machine was invented? You will probably answer around 1900 or maybe around 1600. But if I told you it was more than 5 thousand years ago, would you believe me? Let's take a look at some facts which will destroy your doubt and force you to consider our ignorance of the past.
"What?" You are probably asking. Yes, some flying machines existed in ancient history, and they have been described in ancient scriptures around the world. Let's study some scriptures from India, the Mahabharata and Ramayana which have been dated from several hundred years before Christ. These scriptures talk about some ancient events (which took place probably 3000 years earlier or more). These two texts both describe a war between "gods". This was no small battle but an all-encompassing war, which seems much more similar to a futuristic science fiction book. We could label the war described as "atomic war", because the texts talk flying machines exchanging missile fire and using nuclear weapons. These flying machines are called Vinamas and can go under sea like a submarine or in the sky flying like a plane. The texts even describe how to recharge them with some sort of energy and the specific diet of the pilot. Another text, the "Vaimanika Sastra" describes how to build them!
There are so many details that it couldn't have possibly come out of nowhere having never seen some sort of real spaceship, so it must have been real. What's even more incredible is that there was an Indian emperor called Ashoka who believed so much in these texts that he was afraid that the spaceships could be built. So he hid all the texts mentioning these flying machines and weapons from his people. Like Ashoka, Hitler also believed deeply in these texts, so he sent a team of top scientists to study these texts further and look for some real spaceships. Nobody ever found material facts supporting these text-- at least not publicly. But does this mean that they never existed? Of course not, because there are several reasons why we haven't found them. Suppose for instance that a cataclysm had happened, the civilization who built these machine left the Earth with them. Furthermore, descriptions of these flying machines can be found all over the world, in various drawings and models. We should also note that not all the Sanskrit scriptures (from India) have been translated. We still have more surprises waiting for us !