Question: Is there a limit to the number of tiles a city can work? I've noticed that I can purchase and use tiles several spaces away from my city. How far can I go?

Answer: 
Up to 3 hexes away, 36 hexes total
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Plus one more for the hex the city is on.

***Civilization 5***

![alt text](https://i.stack.imgur.com/MLH64.jpg)

All of the previous games in the Civilization Series used squares for the grid, and the maximum city radius was *2ish* squares away. Take a look at the image below for what I mean by *2ish*. (In words, the exact city radius is a 3x3 grid centered on the city, with one square from each corner removed.) That was a total of 20 squares, plus one more for the city square.

***Civilization 4, and earlier***

![alt text](https://i.stack.imgur.com/5LGg3.jpg)
Your cities can get to hexes that are up to 3 away from them, although they all have to be contiguous, so you can't get to one that is 3 away until you have one that is two away connected to it. There is no limit to the number of tiles you can work (other than the limits on your population).