Thank for the info.
There was a peculiar thing that happend to me with the FP in the game I'm currently playing. (v.1.0)
I was building the FP and lost 3 towns (remote colonies) to the Greeks. Then I noticed that in the city that was building the FP, the production was switched to someting else, and the FP was no longer build-able.
I was a bit puzzeld at first, but I think this was due to my empire dropping bellow the number of cities needed to build the FP. Well, there's a first time for everything, isn't it ?