I pointed in the past our poor performance in GNP and income.
I think that building marketplaces will change that in better.
Do not forget the normal use of caravans : exchanges and trade roads are good for money.
About shields, we are already first in Mfg goods : let us balance grassland for food and growth, plain for mixted use and hill or forest for shields.
And remind : railroad in forest or on mined hill increases the shield production ! But transforming grassland is a long process, even for engineers.
I'm against general transforming and prefer irrigation, mining and road or railroads (we'll have to connect our cities with railroad after its disovery).
