For a memorable history lesson, check out the crumbling remnants of Cahercommaun and picture how it would have looked in its heyday.
You'll have no end of sightseeing choices when in Carran. Cahercommaun is a great place to begin here, but there are plenty of other worthy sights to experience. Aillwee Cave, Burren National Park, and Newtown Castle are not far from the once-important structure and and will cap off your day nicely.
