A while ago there was an interesting thread, even if it lacked comments, about how the history of Welsh football could have been different had there been a Welsh league that all Welsh teams competed in from the beginning.
Skip to Glasgow, and despite them playing each other at least 4 times a year, there seems to be no love lost between Celtic and Rangers. Indeed, the interest and desire to win is as strong as it has probably ever been and shows no sign of diminishing.
In the thread I mentioned, someone brought up what might happen had we had two football league teams in Cardiff. While we'd probably have been the smallest city to have had this, it probably wouldn't have been beyond the realms of possibility.
So, how would it have worked out? Cardiff City vs Cardiff xx? North vs south? West vs East? Would that rivalry have spurred on both sides and made Cardiff more of a football city? Would they have detracted from each other and resulted in two crap sides? Who knows, but it's an interesting hypothetical question.