Something I've noticed about Unit upgrades

[Aabraxan]

I usually just sell Education to the owner of the GL as soon as I get it. Nothing like making them pay for something that makes their 400-shield wonder obsolete.

actually, as soon as anyone researches Education the GL becomes obsolete.

Actually, no. The GL goes obsolete when its owner knows Education. If you do not know Education, you can benefit from the GL (by capturing it, for example), even if everyone else on the globe knows Education.

 

[Verarde]

You need barracks, and also I believe the resource needed must be connected to the city for you to be able to upgrade. Correct me if wrong.

 

[civ4lyfe]

yea, I just aim for Sun Tzu's AOW now. It's much easier to just get free upkeep barracks on all your continental cities.

 

[Theov]

You need barracks, and also I believe the resource needed must be connected to the city for you to be able to upgrade. Correct me if wrong.

Yes to upgrade.
You need it connected to your and their capital to trade.

 

[marceagleye]

If you build Sun Tzu's you can then sell your barracks in every city that already had a barracks before Sun Tzu's was completed. I actually do this the turn before completing Sun Tzu's to save maintenence for that turn. I make exception though for any city that is due to complete a ground unit that same turn to guarantee the new unit is a veteran instead of a regular. You can use this same trick with granaries/Pyramids completion in one turn. I don't do it with temples/Temple of Artemis though because T of A eventually becomes obsolete and you'd have to rebuild those temples if they were a necessary part of your strategy.

 

[Bowsling]

Plus, the counter on the double-culture for temples is reset if you sell it.

And, if you sell the granaries, you lose the food stored there.