Question

Today's architect would not think of building a large unreinforced stone or masonry building in most of the world because of the danger posed by earthquakes on such structures. Yet many huge unreinforced classical and gothic buildings stand today. The Parthenon, the Pantheon, and the gothic cathedrals are all examples. Why could ancient builders do what we are unwilling to attempt?

Answer

For the most part these ancient structures relied upon the mass of the stone work and the friction between stone surfaces to resist external forces. If building codes would allow it, such structures could be built today, but the huge amount of material and skilled labor required would be hard to justify when lightweight and thin-walled reinforced structures are possible.