I notice the Mosque towers sticking up on the middle left side of the photo. In 1969 I spent the night in a hotel room that looked down into the Mosque grounds. (I was escorting American prisoners to a court martial) I'm wondering if yours could be a similar view but lower floor. At the time it never occurred to me that there could be a Muslim population in Vietnam. I thought it was Buddhist of some nature. It wasnt until I returned in the mid 1990s that I realized it was Muslim. I was allowed to video tape the prayers of both men and women at the time (1995). On later trips back they wouldnt allow it.
The Mosque is just a block off Tu Do street (now Dong Koi)