I have a Great Engineer, have Corporation and Railroads, and have a crapton of the needed resources (coal, iron, copper, silver, gold)...yet I can't build it? Is there some limitation on where you can build a corporation?

State Property ? - under which civic, Corporations have no effect and can't be built.

in 3.13 you cant build in mercantilism either

Possible Reasons
1. Mining inc has already been founded
2. You are in State Property (or Mercantilism and don't have the unofficial patch that fixes that problem)
3. You are trying to found it where a competing HQ (Jewelers, Creative constructions, Al co) has already been founded

State property :blush:

those darn communists had to ruin corporations for everybody... but i guess that +10%:hammers: and +1 workshop food makes up for the lack mining company