There's the catch. Carthaginian (yay!) units can't cross mountains without a great general appearing first. That would have to be one hell of a starting warrior.
I realise I'm now actively arguing against my original idea.
You know, they should make that an achievement: gain over 200 XP with your starting warrior - and to do that you'd need to be at war with an AI civ, you couldn't just fight barbarians - get your GG, settle your first city on the single-hex zone surrounded by mountains. All the while not losing your settler to barbs.
This is dependent on whether or not you can even get a GG without founding your first city, of course.
I'm also not advocating this as an actual strategy. But it sure would be awesome to do.
Hardrocker: invulnerability isn't the same thing as efficiency. Sure, your capital wouldn't start off with workable tiles, and would suck for most of the game, but the tradeoff is that nobody will take it, ever. If the game is set so that you can only win via Domination, then with an untakeable city, you could never lose.
EDIT: This is the released info for the Mayan UA, found on the CiV Analyst site:
The Long Count (Maya): After researching Theology, receive a bonus great person at the end of every Maya calendar cycle ( 394 years ).
EDIT EDIT: Blast, ninja'd.