Pyramid question

[HoldSteady]

Still playing civ4 vanilla, but BtS is ordered and underway..

But I have a question about the pyramid. The description says you can use all civic's (I take that as not having to research them). But, when I build the pyramids the other day, it seemed to me I still couldnt switch to newer civics (except slavery which I allready had). Anyone can enlighten me?

[DaveV]

Pyramids let you choose any civic in the Government column only (i.e. Hereditary Rule, Representation, Police State, Universal Sufferage).