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.
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.
https://en.wikipedia.org/wiki/Berne_Convention
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.
