"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 believe the most important aspect of Medicare is not the structure of the program but the guarantee to all Americans that they will have high quality health care as they get older.