This is a speculation, rather than a certainty, so I'd be interested in what everyone else's experience is.
I have just completed 50 Wonders Built challenge, on my 14th game, with easily over 200 wonders completed at this point. I'm not sure where I got my 10 & 20 done, but the last three - 30 Built, 40 Built, 50 Built - have all completed with a Modern Era wonder.
Therefore, I have a suspicion only the modern wonders count towards it. I imagine I completed about 3-4 of them before the game is won, so the numbers would track.
I have just completed 50 Wonders Built challenge, on my 14th game, with easily over 200 wonders completed at this point. I'm not sure where I got my 10 & 20 done, but the last three - 30 Built, 40 Built, 50 Built - have all completed with a Modern Era wonder.
Therefore, I have a suspicion only the modern wonders count towards it. I imagine I completed about 3-4 of them before the game is won, so the numbers would track.
