"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.
You can learn as much about the history from reading about the present as you can vice versa, that is learning about the present through history, which is what I do for a living.