I think civ 4's interface is much more complex and better then 5 or 6, and just discovered something that I can't seem to find discussed here, or anywhere for that matter. I tried google, but nothing. Anyways, if you press the plus or minus key on the numbers pad on your keyboard, a city will come up with the borders of that city's workable tiles highlighted. If you continue to press the plus or minus keys it will cycle through your cities with the selected cities workable tiles. You'll see circles over the workable plots within that cities range. The circles are 4 different colors, red, green and yellow and blue. Red seems to be a plot you can either improve a different way or an unconnected resource, green seems to signify it's all good, blue seems to be tiles the cities not working, and yellow just seems to signify it's a water tile. Is there something else I'm missing about this feature? Also why isn't this front and center in many strat guides on how to improve cities? Once I get this figured out it's going to be so much easier managing my workers.