When we arrived at the passage tombs at Carrowkeel, the skies above Boyle, Ireland were gray and there was a light misting rain. We had the remote hillside to ourselves, and spent a quiet afternoon exploring many of the 14 Neolithic cairns, which were built around 3200-2400 B.C., and consist of a short passage leading to a central chamber and satellite chambers. The builders arranged the cairns to face the sunset, and as if on cue the sun made an appearance just as I stepped out of one of the tombs, greeting me with the most spectacular rainbow I've ever seen