"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.
Tuesday the 29th of October 1929 is one of the world's most infamous Tuesdays, known as Black Tuesday. This is the day of the Great Stock Market Crash, the event which catalyzed the Great Depression in the run-up to World War II.