# https://www.youtube.com/watch?v=lX1FndaE63o
# by @StoneRiddles

2024-12-26

@JorgeStolfi
1 month ago
Mirko, thanks for your systematic tours of megalithic ruins!
However, you must note that a polygonal wall, even with huge blocks and paper-thin joints, is FAR easier, cheaper, and faster to build than a "lego" one with rectangular blocks.  
To make a rectangular stone "brick", one must find a raw stone of the proper size, then chip away a lot of rock.   On average, that will be more than 50% the volume of the original stone.   
In contrast, to build a polygonal wall, one must look for a raw stone that roughly fits onto some notch on the upper edge of wall built so far,  and chip away only as much is needed to get perfectly matching surfaces -- whatever their shapes end up being.  The amount of material that needs to be removed from both sides of the joint can be very small, say less than 5% of the volume of the new rock.  
"Lego" walls of make more sense than polygonal ones only when (1) there is a strong aesthetic or engineering  justification for them, such as around doorways and at corners of walls; or (2) there is no regard for the amount of work needed, such as when the wall is built by a large contingent of slaves; or (3) the stone is to be quarried from a massive rock formation, such that the blocks can be produced directly in "lego brick" shape by well established sawing or splitting techniques, with minimal dressing.  In the latter case, since quarrying is far from the place where the wall is being built, the standardization of block sizes and shapes makes wall building trivial, and the total amount of work (quarrying, transporting, erecting) may well be less than that of building a polygonal wall.

@StoneRiddles
1 month ago
Thank you for your comment. I'm still not sure that polygonal walls are so easy to build. There's many places where there are km and km of walls, so it would be pretentious to consider that all the blocks were just found at and around the site and then adapted for each "position" in the polygonal puzzle. And, as you very well point out, at the moment you have to quarry the stone, it's much more logical and easy to quarry it directly in standardized, parallelepipedal shape. I've seen such ancient quarries, and you can still recognize the squares that were quarried from the living rock. Furthermore, in this video is an example of how some people do polygonal walls today https://www.youtube.com/watch?v=nSs_qrM_5No. It doesn't seem easy to do a similar job but with 500+ kg blocks, especially if you want very precise joints. Cheers

@JorgeStolfi
1 month ago
 ->@StoneRiddles  My point (that seems to be often overlooked) is that IF the stones are not quarried systematically from a massive rock formation, it takes a lot more work to make one or more rectangular blocks from a natural boulder than to sculpt it and the underlying wall blocks to obtain a precise fit.
We unconsciously tend to think that the boulder would be turned into a rectangular block by sawing, or by splitting it with wedges as is done in quarries; so that part of the work seems relatively trivial.  But in the context of the polygonal wall builders, neither method would be available.   So making a rectangular block would mean chipping away the unwanted rock with  stone hammers and/or chisels; which on average would be about 50% of the volume of the original boulder.

2024-12-26
@JorgeStolfi
1 month ago
By the way, paper-thin joints have a strong engineering justification.  If the stone surfaces do not perfectly match, the stress from the weight of the wall above a given block will be concentrated onto those few spots where that block touches the block below, making it much more likely to crack.   To reduce this risk, the gaps must be less than a millimeter, so that the blocks touch in many well-scattered places.  That is why dentists spend so much time ensuring that teeth and fillings have well-matched shapes...