What is the significance of the BFC

[paintanker]

So I hear all this stuff about the Big Fat Cross, but I don't get why it's so important. A city's borders are only in that shape for a few turns, then they expand. Why should it matter if a resource is in that space or not?

Edit:

So, does it help at all to build regular farms, cottages, and mines outside of the BFC?

 

[Flayed One]

Because a city can only work tiles that are inside BFC, even if the culture borders are further.(note that improving the tile and connecting it via roads/rivers with trade network will provide the resources benefit to your empire even if it's not in BFC of any of your cities)

 

[Ghpstage]

The BFC is what you get after the first expansion, and contains all the tiles the city will ever get to use for yields food:, , ).
Even at legendary culture, a city can only work tiles within the same BFC, a 5*5 square with the corners removed.

 

[drlake]

If all you care about is gaining access to a resource to improve your civilization or for trade, it doesn't need to be in the BFC. Of course, a lot of the value comes from working it, hence all the focus on the BFC.

 

[Ray Patterson]

So, does it help at all to build regular farms, cottages, and mines outside of the BFC?

Rarely. Farms may connect irrigation of course. And very rarely mines will find a resource, though that's not worth the trouble I think. Cottages serve no purpose outside fat crosses.

 

[Ghpstage]

And very rarely mines will find a resource, though that's not worth the trouble I think.

I'm pretty certain this can only happen if the mine is being worked.

So, does it help at all to build regular farms, cottages, and mines outside of the BFC?

Usually no, the already mentioned irrigation from farms and in order to hook up resources (mines on copper etc) being the exceptions.

 

[Wreck]

Rarely. Farms may connect irrigation of course. And very rarely mines will find a resource, though that's not worth the trouble I think. Cottages serve no purpose outside fat crosses.

Chain irrigation is a big use for extra terrain.

Everything built outside a BFC can slow an enemy down because they like pillaging. Though this gets them money -- not necessarily what you want.

You cannot get extra resources in unworked mines. You can, however, put up mines (and road connections) to all hills in the hopes that when you get particular techs that unlock particular resources, you'll happen to have a mine already done.

You can also build forest reserves outside of BFCs to culture forests. Forest reserves make them far likelier to spread, enough that you can chop a forest, then grow it back -- if it is adjacent to lots of reserves. Don't build roads places you hope trees spread. Note that it is probably superior in terms of optimal play to just chop all forests as soon as you get them in your culture. But if you like pretty trees, and you've got lots of worker-turns to burn (as in a OCC), then it can be fun to culture forests.

 

[Gr8scott]

You will almost always want to develop any resources that are inside your cultural border even if they are not inside one of your city's BFC.