Pozzo sacro di Sa Testa is a secondary but useful sight in Olbia, the sort of place that rounds out an itinerary once the obvious highlights are covered. Its location makes it easy to combine with a walk through the surrounding part of Olbia.
It is worth checking current access before going and pairing it with nearby stops. Give it enough time to be more than a pin on the map; the smaller sights often work best when you arrive with curiosity rather than a strict schedule.