Civilization – What social policy reduces border growth via culture

You will accumulate Culture Points even if you already have enough points to buy a policy. This can be very important strategically:

• If you build the Cristo Redentor Wonder (or are close to building it) you should wait to buy your policy until after it's complete, in order to gain the 33% discount.

• If you build or annex more cities the cost of future policies goes up, so you should purchase your next policy before obtaining a new city.

As far as not wanting any of the currently available policies, sometimes you have to just take a non-ideal policy to open up future policies you DO care about.

You can see which tile your city is going to go for next by opening the city screen and looking for the hex with a purple border. It definitely isn't random, it tries to pick the "best" tiles. Generally it seems to go for resources first, but it also doesn't seem to go for tiles that are 3 hexes away until it has gotten all the ones that are two hexes away. Of course, you can always purchase a tile yourself if it is one you really want.