The Sphinx: Golden and Plastic

The Great Sphinx at Giza is arguably the oldest, most famous and recognisable fixed statue on Earth. The consensus is that it started as a monolith or yardang, before being carved and later renovated to that of a feline with a human head. The Sphinx is oddly proportioned and positioned relative to the rest of the Giza plateau, with the distinction of facing directly due east. Its position is however not random, but mathematically determined using both the Golden and Plastic ratios. These two constants have unique arithmetic and geometric properties. The Sphinx's location and dimensions lead to several references to $\pi$ and other favoured irrationals, continuing a theme prevalent in the rest of the Giza site plan. This raises questions about who built it, and when.