Older than we think.
Sphinx water erosion hypothesis
https://en.wikipedia.org/wiki/Sphinx_water_erosion_hypothesis
Fossil Suggests Egyptian Pyramids and Sphinx Once Submerged Under Sea Water
https://www.theepochtimes.com/fossil-suggests-egyptian-pyramids-and-sphinx-once-submerged-under-sea-water_1274558.html
About 38,000 and change to get all the astronomical references to come together?