The Great Sphinx at Giza in Egypt is the oldest monumental stone sculpture in the world, and still the largest. At 74m long by 20m high, not even Mt Rushmore (at a mere 18m) can compete. The mouth, with its enigmatic smile, caused by erosion and ancient vandalism rather than design, is 2 meters across. It was carved from the living rock - one of several limestone knolls in the area. The body, heavily eroded, is a soft yellowish limestone; the head is of a much harder grey limestone. It faces due east, directly at the sunrise at the solstice. The neck is particularly badly weathered, because it was vulnerable for the very long period when only the head was visible above the sand. Herodotus, who has much to say about the pyramids, does not mention the Sphinx at all - maybe it was completely buried in the 5th century BC. …