"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 knew I really made it when my dad saw me in London and after the performance he had no notes to me and just said 'You are doing your own thing and I am proud of you.'