"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.
In my books the technology that I choose to talk about has to serve the themes. What that means is that I end up having to cut out a lot of cool technology that would be really fun to describe and play with, but which would just confuse everybody. So in 'Amped,' I focus on neural implants.