We're fast approaching the industrial age (which we should be at, at about 500AD - it's about 50 turns or so quicker to each age on the next higher difficulty), and we should plan ahead. Below is a map of where I think our next cities should go. (Ignore the northern gem-city for now)
This is if we manage to conquer the Japanese. You can sort of get the picture where our Forbidden Palace should be. The proposed city NW of Hakodate could be moved north or south to fit another city in there. But, if we want to be war-like, then we should have numerous productive cities, and some idea what we want them to produce. Artillery? Tanks? ICBMs? Wonders?
Notice that grasslands give us 2 food. If we irragate and railroad all of the grasslands in a given city radius, it gives us 2 food each to support the mountain tiles, or 2 food to support 2 hills. Plains only give us 1 extra food (with a 2-food base), so that's two plains for 1 mountain, or 1 plains for 1 hill.

This is if we manage to conquer the Japanese. You can sort of get the picture where our Forbidden Palace should be. The proposed city NW of Hakodate could be moved north or south to fit another city in there. But, if we want to be war-like, then we should have numerous productive cities, and some idea what we want them to produce. Artillery? Tanks? ICBMs? Wonders?
Notice that grasslands give us 2 food. If we irragate and railroad all of the grasslands in a given city radius, it gives us 2 food each to support the mountain tiles, or 2 food to support 2 hills. Plains only give us 1 extra food (with a 2-food base), so that's two plains for 1 mountain, or 1 plains for 1 hill.