"Ahu" are stone platforms on which many moai sit. There are 313 known ahu and 125 of these carry moai. The biggest, Ahu Tongariki is 220 m (720 ft), and had the most (15) and tallest moai.
The reason for the slow progress of the world seems to lie in a single fact. Every man is born under the yoke, and grows up beneath the oppressions of his age.