50/50 on what to think. The pyramids being a map of the stars is intriguing and shows how ancient man did some amazing things. But it could have also have been just a tomb, but why was it so plain and looked liked it wasn't used?
For reference I watched this video on it last night. The end of the video does get a bit ancient aliens-y but thankfully doesn't go too far. Great channel btw.
Wild Card Answer: They were indeed massive grain silos :ben-carson:
Yup, if you know what to look for in any old city in Europe, pretty much every pre WWI building has elements of stripped older structures. Really common throughout countinously occupied spaces.