That plain word, used by archaeologists to describe a bounded space whose original purpose is not always clear, covers an enormous range of human activity. Enclosures in the Irish landscape might be the remains of a ringfort, the curving bank of a cashel built from dry-laid stone, the outer wall of an early ecclesiastical settlement, or something older still and harder to name. The fact that one sits in this particular corner of Mayo is, on its own, a small and quietly interesting thing.