First mentioned in Part 1, there is a limited area in which you can erect improvements to have them still be apart of your city and in cases of neighbour bordering issues within your civilization's territory period. Each one of your cities carries an economical as well as a cultural radius of influence inherent in its very existence, so if you want a city to exert authority on a structure you must raise it within these confines. There is more to the equation, though: you don't simply want to build an improvement for the sake of utilizing what may otherwise be vacant land. Moving the placement of a city improvement by as little as one square north, east, south or west of a given position can make a noticeable difference in the productivity of that improvement. Case in point is that of a woodcutter's camp. As demonstrated by Reynolds, the more trees the camp is placed in proximity to, the more Citizen units it will be able to employ and increase output correspondingly. For those of you familiar with Chris Sawyer's Transport Tycoon and follow-up Transport Tycoon Deluxe in the early and mid-1990's, this is similar to the necessary custom of placing depots, harbours, train stations and airports around natural resources and urban centres to maximize their usefulness.
Farmlands act as irrigation of terrain in the Civilization series. While each of your cities can only support about five farms, you can improve their efficiency by building a Granary although as logic would dictate its effects only apply to the city under whose land it is built on. All you have to do is make certain you have a sufficient commerce level to reach this point; if not, then go to your library and read up on more commercial technologies such as Coinage.
Unlike many real-time strategy games, resources in RoN do not deplete over time. In accordance with our earlier example, there is no complete clearcutting of forests to be exercised. The game forces a 'sustainable development' practice on you, the player, where it recognizes the environmental limitations of how many people an area can support working on and taking from it at any given time. As cities grow progressively larger, its architectural structure changes dynamically to reflect this consideration.
RESPECT THE BOUNDARIES OF THY MOVEMENTS
The girth of your civilization's national boundaries can swell by building not only cities, but also the improvements to support those cities. For example, in your library research the necessary technology to advance to the Classical Age to then build a Temple, thereby increasing the power of your religion and in turn bush your sphere of influence outwards.
Sooner or later there will come a time when you find your boundaries bordering that of another nation's. If you desire more (and who wouldn't?), you can overtake territory by employing one or more methods. The standard means is, of course, by military might. Another albeit similar means is to build a fort; in doing so, you not only increase your boundary, you also decrease your enemy's from which you just acquired land be it the computer or another human player.
Reminiscent of the Civilization and Age of Empires franchises, a mini-map showing territories across the simulated world you find yourself on is displayed within Rise of Nations' interface by default. From here, you can observe with a glancing eye who controls how much territory and where that territory is situated. If you take this to mean that each civilization is colour coded for easier representation like its turn-based forbearers and real-time cousins, you would be correct. In recognition of these national boundaries, any plans you may draw up to covertly construct a military installation inside these invisible walls are not worth what they are laid out on.
Rise Up: Reynolds On RoN 
