Hanging Gardens of Babylon.
35 size city ftw
Leo's Workshop.
That would be ftw, if it was possible.
Question: I built Leo's workshop (also my fav wonder) last night and it upgraded all of my warriors/legions/horsemen untis to knights, but it didn't upgrade my archers to riflemen even though I had discovered gunpowder a few turns earlier. I DID start and finish researching gunpowder while the workshop was being built... Is that why my archers didn't upgrade??