619
I looked all over for a date and got everything from "early 1800s" to "late 1800s" but nothing exact, so I had to make an educated guess. The first cameras practical enough to take such a photo were developed around 1840 and the excavations began in 1867.
i was getting ready for forty winks
when, lo, up popped this post on the Sphinx;
that ensued in a long stroll
down the wikipedia rabbithole
and a whole host of now-purple hyperlinks.