How do national borders work?
Your national borders define a territorial region projected from your cities and Forts. Each of these build types push out your borders and their “border pushing” effects may be enhanced through research. The amount of push created by your cities are enhanced by the level of research in the “civics” track (these are the cyan colored research line found in the library). The amount of support buildings within your city which upgrades the type of city it is also increases the border pushing effect of the city. In addition, the temple gaves access to a “religion” line of research to further enhance this effect. The border pushing ability of fortresses can be increased by advancing the “fortification” line of research accessed within your fortresses. A nation can increase its borders also by building the Temple of Tikal, Eiffel Tower or the Colosseum Wonder. There’s no practical limit to how far your borders can push outward from a strong political center other than another nation “pushing
