That's what i thought when he was talking about the Inca rope bridges: much of our modern construction requires so much maintenance that it seems to be closer t

That's what i thought when he was talking about the Inca rope bridges: much of our modern construction requires so much maintenance that it seems to be closer to the annual replacement cycle of the woven bridges than to the near-eternity of stone arches. But not steel and concrete is not only cheaper than cutting natural stone, they are also cheaper than the cheap alternative that dominated the millenia before (even when concrete was available in some periods): bricks, the main architectural workhorse from ancient Babylon to Rome to deep into the industrial age. Exposed brick has a quality of functional beauty that reinforced concrete can never achieve, because there all the function is hidden inside the concrete and the outer shape is completely disconnected from function, either completely plain or arbitrarily ornamented. Brick on the other hand has a visible functional structure, the arches never lie and ornaments (which are never entirely afunctional in architecture: they distract the eye from dirt, and dirt will be unavoidable over time) can easily be included using standard or special blocks and blend in perfectly with the "natural" details that are there for technical reasons. Occasionally i dream up a future that would have swarms of bricklaying bots that would turn architectural drawings into houses cheaper than poured concrete. Never did any calculations though, so i don't know if the price advantage would even be possible with hyopthotical zero-cost robots.