So, I´m playing Egypt and I got a productive start with plenty of wheat and sheeps by moving on top of some copper on turn 1, so I go for a workerless Scout->Monument->Granary->Settler->Pyramids.
Although in a better world free of barbarians it would have been perfectly timed for both my free settler and my built one to finish their Libraries right when I unlocked the National College, a war-axe decided to camp on my precious hill and it would take me about 10 turns to bring a warrior to escort the settler in position.

So I finish my pyramids the same turn (42) I find a ruin for my 5th citizen on the capital (which was stagnated), and I´m torn in this awesome and kinda frustrating scenario (Alex is my neighbor, if I don´t finish the national before turn 80 to build up and attack him asap, either he will do that to me before my pikes or he will start allying an impossible number of CS as always) - and the Great Library is avaiable costing 12 turns.

So, in view of the very possible fact that Alex is coming, I say "eh..." and go to reveal Iron and try the Great Library for free Swordsmen (I had a huge desert between my 2nd and 3rd cities, no horses at all, very likely I´d have iron, turns out I have 2 :/ ).

and bam! achievement unlocked.

My brain even farted for a second there when I checked which achievement it was - "Build all wonders throughout any number of playthroughs" - and I was like "but I didn´t...ooooh". I had never built the Great Library in my own steam.