"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.
There's a tremendous difference between alone and lonely. You could be lonely in a group of people. I like being alone. I like eating by myself. I go home at night and just watch a movie or hang out with my dog. I have to exert myself and really say, oh God, I've got to see my friends 'cause I'm too content being by myself.