Just got great library on turn 31 on deity mode civ v vs 7 ai.
It take hailmary to achive this.
I almost lost it just 1 turn to ai.
Im literally 1 production short of 185(have 184) before ai beat me.
So i row mysave back 1 turn and buy a single tile just to produce 1 production more to beat ai in a single turn.
However the most rng thing to achieve this is to get the right free technology from ruins in turn 10. Which i think is like less than 1 in 500 chance or something.
Then i must start building great library asap and even let my city starve for a few turn.
I also successfully get 9 ruins before no ruins left.3 of them is upgrade my unit.
One thing that i did pretty bad in this rub though is i only got my policy on turn 25 which is very late since i ony produce 1 culture per turn and not a single ruin gave me culture.