Quote Originally Posted by Ludens
Correct, except that temples also give a big cultural penalty. Tearing down foreign buildings is not necessary: upgrading works just as well.
I'm not sure that temples have that much effect on culture penalty.

The governor's building dominates. If you have the wrong governor's building, it seems very hard to get culture penalty below 40. Max is 50.

Tearing down foreign law/happiness buildings to improve culture penalty will generally hurt you until you get your own governor's building built.

I tend to immediately knock down buildings with no order benefit that I'm not going to use (e.g., military buildings and blacksmiths in a city I don't want to use for troop production). This gets a little cash, starts the re-culturation, and makes the city less valuable to the enemy should you lose it. I might knock down the temple if it's near the low end because it can be quickly rebuilt, and then grown beyond what it was. I might knock down the market if the build queue is idle, but I can often just overbuild it. After I get the opportunity to build a new governor's building, then I will usually take the final steps to purge the old culture. The primary exception being those temples which give huge experience bonuses, which are great to keep.