Yes G1's Mortuary Temple may have been different in construction and layout, maybe granite pillars instead of massive limestone blocks, but if they got them made and put up then i guess they could be brought down and repurposed by the same method.
Yes. I agree that was most likely the case.
The Mortuary Temple was entered via a doorway in the eastern wall. Sockets in the basalt pavement mark the location of megalithic granite pillars that once surrounded an open court.
I am aware that there were granite pillars in the temple (I've even included an image of a base of one in the OP). However, I do not agree that these pillars were megalithic in size.
Here's a thought, what if the missing granite pillars found there final resting place in a place what we now call the Osireon.
Possibly. I guess that this would present a dating issue and may be a difficult challenge.
...are they from other planets or other dimensions , but could it be possible they are actually from our past, did we reach a much more advanced civilization than the one we are living in now and achieved time travel, or maybe its the other way round , our future selves coming back in time.
In the infinite realm time ceases to exist. Einstein proved this mathematically with his equation E = mc2. Translating this calculation into language, it means that when a body reaches the speed of light, its mass becomes infinite and time ceases to exist.
Therefore, one only has to become light to achieve this state and then the whole universe, both gross and subtle, opens up, including past and future time.
This ability is not achieved by reaching the speed of light in a machine, but through a human process - the light body. This, I believe was the goal of an elite few, and reached through what is termed Ascension. However, TPTB, claim that Ascension only happens after death and confuse it with Ressurection (a la Jesus), whereas it can only happen when one is alive. The Jesus teaching is correct in the need to be born again but misunderstood, either intentionally or misguidedly.
The pharaohs who ascended understood all there was to know about the physical world and its discreet powers. It was their duty to maintain Maat for the benefit of the people and that is why the Heb Sed festival was important to ensure that the pharaoh was sufficiently capable of continuing to be the Savior and Preserver.
Why "The Book Of Coming Forth By Day" was changed to "The Book Of The Dead" makes no sense because the ancient religion of the AEs was not that of death, but of life. Unas went to the stars while alive - in his light body. Unas was Horus. And so was every other Ascender. Because in the infinite state, all is one. God is Horus. Horus is Unas. Unas does seemingly magical things, just like every Horus can do. And which we still cannot do even with all our modern machinery. Well, we could if we became Horus. And that's possible. That's the mystery.