Improvements as prerequisites

[Jer8m8]

In order to research or build some things, you should need to have built city improvements. Here are my ideas:no spaceship parts in factoryless city, naval base for battle ships etc., factory (production line?) for mobile infantry, plants for building airplanes. Also for techs. Maybe you will need to have a research lab in x cities in order to research some techs. And with the CIs for building stuff, ?>?>blacksmith shop>?>factory>assembly line>manufactoring plant>Robotic assembly?(something futuristic)

[Grumbold]

I can see your point with some manufacturing tasks but Civ has always been a very macro game. When you rush manufacture 20 marine units in 20 cities on one turn, is every city making its own armaments or are the troops simply being trained there while the guns are shipped in from the industrial heartland?

On tech, I think it would be nice to require some form of academic level to sustain new scientific advances, but that is about it. One city with a university is enough to produce a Pasteur, Newton or Einstein. You aren't likely to be making the breakthroughs without a higher level of support anyway. In a democracy it may be the corporations that have build a powerful electron microscope improvement even if the State hasn't publically admitted having one.