What it does is work exactly like Hope. The building is there only while the resource unit is there. The building creation modifies the duration of the unit. The unit is destroyed and so is the building when the duration expires. Thanks that's a great idea using some of the unused unit fields to store values for culture, production, population, etc. I'll look and see what there is to use. Gold is not stored - is the gold amount that civ has tied in to cities?