"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.
I am 65 and I guess that puts me in with the geriatrics. But if there were 15 months in every year, I'd only be 48. That's the trouble with us. We number everything. Take women, for example, I think they deserve to have more than 12 years between the ages of 28 and 40.