OK, here comes the easy way:
You play wonderrace (scroll down where you select the game mode to find this mode) with the following settings:
Starting age: Post imperial
Starting ressources: very high or maybe even infinite works
Your civ: Spanish (Spanish villagers build 30% faster)
AI civ: One that doesn't get the tech Treadmill crane, for example Goth
Now when the game starts instantly start building a wonder.
Delete your scout, cue up a lot of villagers and set a rally point to the wonder. New villagers will automaticly go build on the wonder. Maybe you have to move them a bit from if the pathfinding messes up.
Let one villager build a few houses.
Now there should be no way for the AI do be faster than you.
Not only will you unlock this ach, but also: