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.
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.