Baile Atha Cliath (the town of the ford of the wattles) is the official Gaelic name for Dublin Town(City), but Dublin is as said above also derived from a Gaelic name meaning Black Pool. They were originally (as far as I know) two different settlements along the banks of the River Liffey, which merged into one city - they weren't very far apart to begin with (maybe half a mile). Atha Cliath without the Baile means Dublin as in Condae Atha Cliath (County Dublin).