On Tongatapu the central place of the rising kingdom of Tonga developed in the fourteenth and fifteenth centuries AD. Marked out as a monumental area with a rock-cut water-carrying ditch, it soon developed as the site of a sequence of megalithic tombs, in parallel with the documented expansion of the maritime chiefdom. The results of investigations into these structures were achieved with minimum intervention and disturbance on the ground, since the place remains sacred and in use.