Modified Planet Features to offer a build option instead of giving any adjacency bonuses.
For example, Ancient Ruins will give +3 to Research or +3 to Wealth depending on what type of improvement is built on it.
Unzip and put in ...My Games\GC3Crusade\Mods\AnyModName\Game
(This is not my idea, I think I saw it somewhere else. Apologies to the original author, I'll add credit if anyone knows.)