I remember seeing many speculations as to how the rocks got moved to their specific positions and in that place (IIRC, around 100 Km from the closest source of that type of rock), but I have been wondering about how they actually got such uniform blocks of stone out of the ground.
As far as I understand, the technology around that time didn't actually use many metals, if any at all, and the process of building a quarry without metal tools seems like it would take hundreds of years.
Has there been any research on the subject of how the people that built Stonehenge got the rocks out of the ground to begin with?
The bluestone (which was used for the smaller stones and was the material that was moved long distance) was naturally formed into an exposed pillared structure. There wasn't a whole lot of "constructing" to be done. Extracting these pillars was probably a fairly straightforward process. You insert a wooden wedge into the gap between the stones, either that action or later swelling of the wedge causes the pillar to detach from the quarry rock formation.
There is a paper from a few years ago discussing the excavations at the quarry.
https://www.cambridge.org/core/journals/antiquity/article/craig-rhos-y-felin-a-welsh-bluestone-megalith-quarry-for-stonehenge/D1E66A287D494205D22881CBF1F6DDE8