Tunnel of Eupalinos

Currency, colonies, cultural coherency (shared language and festivals) along with massive internal competition. Militarily strong city states, within which verbal argumentation flourished. All that was prior to literacy, which hit around 750 BC.

Then one big thing was the development of a philosophical perspective that treated math as the basis of reality. That was also re-emerged as a trigger of the scientific revolution. Attributed to Pythagoras—but he deliberately never wrote anything down. What’s nice about not having written doctrines is that they can more easily evolve. The Pythagoreans, btw, also apparently conducted the first hypothesis driven experiment — testing their mathematical model of musical consonance by generalizing it from stringed instruments (where small integer ratios of string length produce consonance) to bronze chimes (where they found small integer ratios or chime thickness also produced consonance).

The recognition that “all is number” corresponds with (but doesn’t necessarily cause) big leaps in collective cultural progress.

Er, the Romans pretty much continued the science and engineering of the Greeks --the management of water alone was a massive engineering feat that wouldn't be matched for centuries. But mainly science and engineering was killed off by a cult that thought such things were against their beliefs and dogma. They were particularly successful in moving all literature and existing written studies to their cult offices or destroying them altogether. Eventually, the power of this cult waned a bit and science started flourishing again, a few centuries later.