"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.
My dad? He died when I was 19, which is a bad time for your dad to die, because there's an awful lot of things you have to resolve with your parents past your teens if you've been a difficult teenager.