[allmost]

Considering the volume and timescale they probably used multiple methods. Steam fracturing and grinding from slave labor would be my best guess. It doesn’t sound pretty because it is not.

[Dusty Road]

One method not mentioned here is copper saw blades, they were used to cut flint that was then pressure flaked to produce some of the most beautiful blades known. Limestone wouldn't be much of a problem. These flint blades came from Egypt.