I had no indication what this picture might represent, until in 2018 I found a site that helped me a lot. I knew the picture was taken in Sagmatar, and this is what I found: "Eski Sumatar (Sogmatar) - Some views of the underground chamber located below the temple of Sin and containing bas-relief representations of the Syrian Gods amidst representations of the lunar crescent"

For the site see: please inform me if the link gets broken.