How I got a Cultural Victory in 1983 (Noble difficulty)

[dar]

I'd suggest nine cities if you can manage it. Each cathedral requires three temples, so nine cities allows you to build one cathedral of each type in each legendary city.

Actually the first requires 3 temples, the 2nd requires four, the third requires five or something to that effect. I've built 3 of each catherdral with only 6 cities with temples.