Abstract: A cluster of paving elements is formed with a peripheral edge having a re-entrant formation formed between the upper supporting surface and the lower, supported surface. The formation engages a complimentary formation on an adjacent cluster to inhibit relative movement between the clusters. The re-entrant formation may be applied to individual paving elements in the cluster or to the exposed faces of the elements at the periphery of the cluster. The elements in the cluster may be shaped to inter-engage to inhibit relative movement between the elements with in the cluster.