I've noticed in a game that I could improve tiles well beyond what I could actually work on a given city. I have some questions on workers and tile improvements. Is there a set number of tiles that a city can work? Can this be increased? What is the optimum distance to place cities apart to maximize tile resource usage? It is OK to have idle workers? I have 4 tall cities that I'm trying to to grow, but my workers have nothing to do until I research railroads. One of my cities has reached a point that I can no longer squeeze any growth from it despite building and focusing food growth. I thought I would build a town near a bunch of hills and make a production town, but what ended up happening was my growth in other cities caught up and surpassed my production city because of the lack of food tiles. Is there a good guide for determining what kind of production focus a city would get more benefit from?