>>40919324
Some argue they were cast or melted with acid but neither matches the appearance of the stone or it’s material.
The builders just had a ton of time and this is where they put all their effort and skill. There are stoneworks like this in India too, carved during recorded history. Here’s a pic of a cave carved by hand with stone tools. These may be the Barabar Caves. The inside was polished to an almost mirror sheen. They dug these out as a gift to a king at the time. All that work just to give something nice to the king, and this is in India with huge pressures from competing economies. In North America with far fewer people it makes sense that their stoneworks would be more complex.