The enclosure at Tromaun is large, roughly a hundred metres across from northeast to southwest, yet its defining bank is remarkably unassuming, rising only half a metre or so above the interior ground level. A drystone wall sits on top of the bank along its southeastern to southwestern arc, the two building methods layered one upon the other in a way that hints at different phases of use or repair over the centuries. The entrance gap, about four and a half metres wide, faces the east-northeast, a common orientation in early ecclesiastical enclosures, where the positioning of entrances and buildings frequently reflected liturgical or symbolic priorities.