When are the eras?

3 Questions:

1. I just posted this on another thread and a kind poster informed me that it was a number of technologies? Or is a specific tech? I'm still unsure? I would really like to know what the numbers are for the era changes.

Also, here's a quick question of preference:

2. Do you guys like holding off as long as possible on finding some wonders? For example, in the new expansion pack, Camelot automatically upgrades your horseman--but it's a one time deal--so doesn't it behove you to wait until you have 3 or 6 or 9 horseman?

3. Also a preference question:

What are your favorite, wonders, artifacts and great people. No wrong answer here--just what YOU like.

It's sooooo cool to be on this site with you guys! Thanks for keeping the forum fun!

As said in the other thread you posted, the advancement is as follows:
Ancient Era - 0 Techs
Medieval Era - 5 Techs
Industrial Era - 14 Techs
Modern Era - 24 Techs

Please keep your questions in one thread. Sorry for being hard on you, but the answer to your other two questions is discussed heavily in other threads, please look those up. Again, sorry, I'm no admin, but I did find several interesting threads about those other two topics after a simple search so I guess you could as well.