Photo of the Sphinx taken from a balloon before it was excavated. I can't find a date, but based on when it was excavated and the history of photography, some time between 1840 and 1867
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.
Also, there's absolutely no question that it's public domain.
AfaIk, this depends on whether we know the photographer. If the author of a work is unknown, it is deemed to be orphaned. In some countries, this may lead to problems when using the work.
Which country would not recognize a 19th century photo as public domain? Because the Berne Convention, which most countries are signatories to, would absolutely make it public domain.
If the author is unknown because for example the author was deliberately anonymous or worked under a pseudonym, the Convention provides for a term of 50 years after publication ("after the work has been lawfully made available to the public"). However, if the identity of the author becomes known, the copyright term for known authors (50 years after death) applies.
I didn't know the information of that section. As it's very very unlikely that the author of a 19th century photo is dead for less than 50 years, the uncertainty of someone claiming the copyright is close to zero.
Maybe, between two excavations, the wind has partly filled up the cavity of the previous excavation with sand and thus, the progress wasn't continuous.