Just a thought, but isn't it possible they were written while they were still being built, so they would be open to their surroundings and well-lit with natural light?
That could happen with the pyramids, but almost all of those are blank inside.
The Valley of Kings tombs were tunneled deep into living bedrock. How they did, I do not know, but ancient people worldwide seemed to have no difficulty cutting unlimited amounts of stone.
The Valley of Kings tombs were tunneled deep into living bedrock. How they did, I do not know, but ancient people worldwide seemed to have no difficulty cutting unlimited amounts of stone.