Apart from the obvious military advantages of the tighter formation, such as being able to move units from one town to another within a turn - in effect, moving and attacking with a newly built unit from the core - arguments in favour include "using all tiles" and "making the best of high-yield tiles by sharing". I'd say those are non-arguments, at least on normal to huge maps. First, of the 20 workable tiles around any town quite a few are low-yield such as grassland, desert, mountains, jungle or swamps. With C-X-X-C, these tiles will have to be improved and worked which is a waste of worker turns until Replaceable Parts. Furthermore, quite a few cities will stop at pop 9 or 10 because of a lack of food even if every tile is improved and rail-roaded. In the core, this means wasted production. On the periphery, they won't make much of being science farms. With C-X-X-X-C, you can work the best tiles which means that in the core, you should easilly get every town to pop 12 with 20+ net shields (republic). In the periphery, your science farms will be pop 12 with no more than 7-8 tiles worked and a minumum of 4-5 scientists (again republic). This is far better use of the available land. Later on in the game, a science farm of pop 35-40 with 15-20 scientists is a regular occurence. Second, the sharing of a cow or wheat between two towns is only an issue during the early expansion phase. It may gain you 4-5 pop points one turn earlier in the secondary town. This translates to two settlers two turns earlier or four workers one turn earlier each than would otherwise have been possible without the sharing of the cow/wheat. Even though the two towns will perpetuate their two-turn start, building everything up to two turns earlier than would otherwise have been possible, that's not much of an advantage except in competition play. The advantage is lost anyway by the third: Third, C-X-X-X-X-C makes much better use of your settlers as it takes far, far fewer to grab more land in a much shorter time span and, incidentally, deny the AI the use of those tiles. Granted, roading the tiles between takes longer, but you want roads on those tiles anyway to gain the commercial bonus. Fourth, town and cities are like cows in a barn - they will go for the best patch and that's invariably at their neighbour's feet even if the equivalent is right next to themselves. This means that you will have to micro-manage as soon as a town gains a pop point. In an empire such as my Roman one in the last game I played (with C-X-X-C) with towns down to "New Rome 3" (not to mention captured ones), micromanaging becomes a nightmare that takes up at least 10-15 mins every turn. This is inefficient use of my gaming time! By all means, swear by C-X-X-C if you want to. Apart from the obvious, military advantages however, there is little to recommend it. Over to you!