District Discount Mechanism was a mysterious thing, but after examination I figured it out today. First, district cost: Spaceport:1800 Others: Cost=(1+9*max(percent of science/percent of culture) researched)*base_cost, usually base_cost=54, except for Aq=36, Government Plaza=30, Cost is fixed upon placement. UD=50% original cost Discounted District: The discounted district costs 60% than its original cost, 75% for government plaza. This discount only applies to districts except Spaceport, Aqeduet and Neighborhood. It shall satisfy the following conditions. 1: a=number of tech/civics you have researched that allows you to build a district (except Aq/Sp/Ne) 2: b= district you have built (require full district instead of district bases, except Aq/Sp/Ne) Condition: 1: b>=a, if a>b no discount is applied. 2: b/a> your total number of that type of district(include full district and district bases) Under such circumstances the cost is discounted for a certain type of district. (except Aq,Sp,Ne) Also, a and b are refreshed if and only if you finish a tech or civic. Mention @antimony , you made a wrong understanding. Only a and b are refreshed this way, and "your total number of that type of district (base+full)" is refreshed immediately. Example: If you can built Holy Site and Campus, while cannot build other type of districts, you build 2 holy sites, you get a=b=2, which satisfy condition 1, then b/a=1>0=num of campuses, so then you get a discount for your first campus. But if you researched Currency before that, then you get b=2 and a=3, which does not satisfy condition 1, in that case you don't get a discounted campus. @Victoria ,I think you have been working on it for a long time, and your idea of the discount only get refreshed when sci/civ being finished helps a lot. Also @c4c6 and lots of other users contributed to this.