"TOTAL TOWN REPLACEMENT" is the goal. The strategy should be the following:
1) Make a set that has fast all types of buildings for all the times.
2) Fill all the slots
3) Move the most unsuccessful buildings when new better buildings appear to the archive
4) As far as many rather good buildings will go into archive (because
other are excellent), start regional subsets.
We can say, that we've achieved the first goal as soon as we come to
stage 4. The next goals can be European and American subsets.
We plan 4 eras - 20-50, 50-80 and 80-2010 and 2010