The design and construction of arches demonstrates a degree of engineering expertise that originated thousands of years ago. One can imagine the process of selecting stones to build a shelter slowly progressing to a more careful sorting and packing to create curved walls that leaned against each other. Eventually the importance of a keystone (or capstone) would have been discovered. Much later mathematicians may have felt the need to describe the requirements for stable arch building ... and the fact that the arches have survived proves the correctness of their formulae.
And then reinforced concrete appeared ...
The photos above, starting top left and moving clockwise, were taken in Annecy, Chambery, Cordes-sur-Ciel and Villefranche-de-Rouergue.