How close should cities be built in Civ 5?
In Civ 4, it was easy to figure out how close to build cities to maximize my territory, because the number of tiles they could use were very limited. In Civ 5, cities can use many more tiles (more than they'll need until they're huge), so I'm wondering how close I should build my cities. Is building the maximum number of cities even a good strategy in Civ 5 (as it was in previous Civs), or should I build a few giant ones far apart?
Probably related to this question:
Is there a limit to the number of tiles a city can use in Civ 5?
It isn't as simple anymore. There's a number of things to think about
Initially your cities will only be able to access the tiles next to them. It will take a long time before your cities are generating enough culture on their own to add many tiles, unlike earlier civs where it was quite easy to boost to a full 2 square radius. So if you need a particular resource, you should either build next to it or be prepared to buy access to the tile.
Once a tile has been claimed, you can't "steal" it like in Civ 4 (except using the Great Artist in the base game, or Great General in the G&K expansion). So you want to make sure you establish your borders quickly before another Civ or city-state grabs those tiles.
Building additional cities causes increased unhappiness across your empire, and it also makes it more expensive to adopt social policies. So while spamming cities early will help you establish a large territory, it will penalize you in other ways.
So while the technical answer is that you maximize your potential territory without gaps or overlap by leaving 6 hexes between cities (since the maximum radius for a city is 3 hexes), I think you will find that blindly following that will be a sub-optimal strategy.
This is one of the systems in Civ 5 that is not necessarily more complicated, but certainly seems to be more strategic than it was in earlier civs.
This is the Furthest Apart you would ever want your cities, if your goal is to work every hex.
There are any number of things that mean you would like them to be closer together:
- Most importantly: cities will only ever be that large late in the game. If you build like that is going to happen, you will be wasting valuable hexes.
- Roads cost money to maintain, so the further away your cities are, the more lucrative the trade needs to be before you start it.
- City-states and other civs will steal the in between squares as your cities are growing. (as bwarner says, establish your borders!)
- Cities further apart will be further from aiding each other for defense.
But you want to use all those hexes don't you? How do you balance?
Build wherever your city will grow the fastest.
The location with the best immediate access to food and reasonable production will be able to produce more money/culture to buy tiles, and you will thus have a larger empire sooner. They'll also be able to defend themselves and other cities sooner, and support trade routes sooner. All of that makes distance matter a lot less.
In short: don't think about distance, think about building a good city.
Also take into account that even with significant overlap, your population can also contribute as specialists. For example, if you have a university in your city, a laborer can be assigned to the university itself (or rather, the specialist slot it provides) rather than to a land tile. This will provide science instead of food or production or commerce. The specialist slot from a marketplace, on the other hand, will provide gold. Although specialists don't provide as much as a well-improved map tile (let alone one with a valuable resource), they do provide great-person points. Specialists can be either merchants (+gold), scientists (+science), engineers (+production), or artists (+culture) depending on what specialist building they are assigned to.
With specialists, you don't have to map out your settlements entirely by how far they are apart, since some overlap is more tolerable now than in past Civs. What's most important is what the city will be able to reach, and also, how soon.
To add to other answers:
Even in Civ4 building overlapping cities made sense from time to time. A city working all squares (21 pop) was rare even then for me, so it made more sense to win a good (resource) tile for a (new) city, even when that meant it to overlap on some average tiles with another of your cities.
Note also that city distance does not affect anything in Civ5, unlike in Civ4 where you got increased maintenance costs for cities far away.
... to figure out how close to build cities to maximize my territory ...
Personally I more and more get the feeling than maximizing territory isn't as important in Civ5 as it was in previous games. Also, luxury (and strategic) resources are far more important to get than to maximize territory, because it takes ages to get a city to it's maximum radius (unless you culture bomb your way I guess). Buying territory for territory's sake doesn't make sense either, because it gets expensive very quickly.
It still seems that building a new city as soon as you can afford one (you need enough happiness, because building a new city will decrease your overall h.! -- if the new city unlocks a new luxury resource, than can of course help.) is a good strategy in Civ5, but I find that other factors are far more important than if a city overlaps another: Like how can I max out good squares for the new city, without stealing important stuff from an existing city, even if that means to overlap 50% with an already existing one.
To sum up: For territory cohesion I would go 4 hexes distance (vs. the 6 maximum) but I would build a city even 12 hexes away, I'd get a good resource for it.