A more unknown pyramid is this Lahun pyramid.
Here is an excellent informative link with video and photos and links:
"When you read this post and watch the video and pictures presented here, compare engineering skills required to build a mud brick pyramid to much more advanced engineering skills required to build the underground chambers and the granite box (made with ultra precision)..."
From: https://blog.world-mysteries.com/strange-artifacts/precision-engineering-predating-era-of-the-ancient-egypt/
Diving further:
https://fayoumegypt.com/lahun-pyramid/
I did watch most of the video and the precision of the tooling on the box is mind boggling. I'm amazed what was done without the modern power tools we have today. So many mysteries in this world.