Why do some tiles have pink borders in Civilization 5?
When you go to buy a tile in Civilization 5, some tiles have a pink border. Why is this?
Solution 1:
Unlike previous versions of Civilization, in Civ V, territory around a city expands one tile at a time. The pink highlighted tiles are the ones that are next in line for expansion through culture. Consequently, they are also usually the cheapest tiles to purchase.
Solution 2:
These are the tiles that your city will next acquire when it expands.