Buildings with a universal effect, such as Industrial Farms should not be built at a planet. They should be somewhere else, so I can easily see that I have them and so that they cannot be destroyed or captured.
And what about your enemies buildings? You want them impregnably located in abstraction? Specific locations for special buildings give systems unique strategic value.
Not all buildings. It just seems that something like Industrial Farms shouldn't be destroyed by taking a single planet, since it represents farms on all industrial worlds. Thinking about it more I think Industrial Farms shouldn't be a building at all - like Orbital Farms and Autofactories.
I built a new Imperial Palace today and kept my old one, so I now have two. When I look myself up on the Pedia my capital is listed as the original one. I carried on a few turns, but no change. My original capital has a supply of 3.00 from the Imperial Palace, my new Palace gives supply of 3.00, with a Space Elevator giving 0 at that location. The palace description claims a +1 bonus.
As far as I can tell the only ways to increase supply are Palace and Elevator. Places other than the Palace should provide supply. Maybe an upgrade for Ship Yard. Or a focus for an outpost or colony. I think building ships should be a focus, since they are a major part of the game and I would think that a single colony empire would need to make a huge effort to build the first colony ship. (With Cultural Archives it would be possible.)
As another thing I'd like to see changed for v.3.18 ... When I check my planets I get the benefits and penalties from focus reported as my species name, not the focus name. This is quite strange for Heavy Mining, Where my population could be:
Federation Tech Subterranean Construction
Federation Tech Transdimensional Housing
I think that later on when species have bonus/penalties this should be marked by species name (maybe followed by the ability/penalty name - like technologies). The Focus bonuses and penalties should be labeled as such.
Also population and health should show enivironmental modifers (such as Hostile/Good), so it is obvious which planets could benefit from terraforming, when I have lots of different species. Mining should be affected by planet size and this should be listed.