When preparing the material for one of the articles, an idea arose that clarified why many places where stone was mined were grottoes, and not open quarries (as they do in our time). But everything is in order. First, I suggest looking at the ancient Carrières de Lumières quarry in France.
Why it is called that - it will be clear from the subsequent photos. The quarry is an artificial grotto, a selected rock inside a rock. These photos are very reminiscent of examples from China. I wrote about them here.
The facility is located 10 km from Saint-Remy-de-Provence.
Official historical sources report that the Romans mined limestone here to restore the Ligurian city of Glanum, and then to build the city of Arles. The quarry was closed in 1935. Perhaps part of the mine workings is not ancient, but if so, then all the same questions remain.
According to the first photographs, the technique of extracting rocks is striking: going deep into the rock in closed ways, and not from above, as they do in our time. On the vertical walls of the grotto, you can see the traces left during the extraction of each block separately. The height of the vaults is 15 m or more.
Promotional video:
The entrance to the quarry where the light show is currently located.
About 70 projectors were placed on the walls and a kaleidoscope of paintings by Leonardo da Vinci, Michelangelo, Raphael is projected onto them. Music sounds, and the acoustics in such grottoes give it unforgettable effects. But behind the beauty of the light show, visitors will no longer see the details, traces left by mechanical cutting of the rock. Most, of course, come here and not for this, but to watch the light show. For this reason, the quarry is called the Career of Light.
The workings are multilevel. In those places where the projectors do not light up the vaults, you can trace the stepwise cutting of each block. On the internet, photos are mostly of this light show, there are no detailed surface shots.
Fast forward to a location near the quarry:
Nearby is the castle of Le Baux, destroyed by order of Louis XIII in 1632. According to legend, it was built by representatives of a dynasty whose ancestor was one of the sorcerers who came to Jesus. A hint that France (formerly called Gaul) is the likely site of many biblical events.
Not the summit is also met by small, man-made grottoes. Apparently, this process at that time was not difficult. This is easy to do if the rock originally had a different strength or was generally plastic like dense clay. Why gouge a rock for a room otherwise?
"Cells" on one of the rocks near the castle. Assumptions: burial sites or poultry house. Cutting this can be easy, but hollowing out is a completely different job, both in time and effort.
According to my hypothesis, these stone outcrops, mountains, appeared on the surface recently, quickly, one might say catastrophically quickly. People began to rebuild civilization anew (somewhere the ruins of antiquity were preserved). We used this plastic or loose rock, because we saw that it turns to stone and does it from the surface (not like concrete based on Portland cement, throughout the volume). Sometimes it was necessary to get to the unhardened masses by laying grottoes. This is what we see in the Career of Light.
The same was done in other places of the planet. Longyu grottoes in China were cut from the inside of the rock for the same reason. Although this is a more time consuming method.
In this article, I made a similar assumption and showed other examples that many caves have been dug. In the video article - an analogy of how it was done.
And again the version with geo-concrete. Someone will write that again it is unprovable. There are no formulas or descriptions of the physical principle of rock strength gain. This is not so, I made assumptions and a description of the possible mechanism of stone formation. For example, here.
And this is how marble is mined in our time:
Koelginsky marble quarry. Our civilization mines the stone in an open way from top to bottom, even if it is possible to approach the massif from the sides. It is also safer - there is no risk of rock collapse. The grottoes are cut out if a closed mining method is conducted at depth.