Most likely scenario is somewhere around Iran Azerbaijan Border. Somewhere around Khudafarin. Composition and type of bridge and basin behind and mountains resembles (Khudafarin Bridges) There are two bridges. Images from area limited (for panoramic view from area behind.). Other bridge, the intact one has 15 span. Portrait may be based on limited description provided by Da Vinci's Mother. So probably overall composition is more important. Also considering background probably intentionally not completed or he was hoping to find more information about area beside his mother childhood memories. It is where his mother is from. There are already claims for his mother's Azerbaijan origin. But It wasn't known Mona Lisa was a such depiction because of intentional misinformation campaign.
It seems like there wasn't something like a lake before dam construction but still river comes from left although probably shouldn't be visible but in the portrait area that looks like a lake at the left not realistic anyway. Although it seems like there were seasonal water accumulations in a very large area. It is possible that due to very favorable geographical conditions maybe there was a very small dam in there in the history. It seems like even few meters of a dam could pool very wide region. There is a basin where water splits to mulitple channels in the area. Though even with a dam the lake like part in the left is not viable. But the region under left resembles the area because turns arid quickly. And it is more of a completed part of the portrait. More importantly probably there is no such arid land in Europe. If we assume higher part of picture is inconsistent because it wasn't completed and evaluate over lower part this scenario is very likely. The region is exceptionally suitable for a small dam although I couldn't find anything about it. But there are two bridges very close to each other which is interesting. Maybe because second one was made because they decided to build a dam. Speculative but especially saying this because dam would be just sitting between them. (image) Although maybe just for redundancy purposes. Historical records regarding when they built or repaired are ambigious. Although both very old and considered co-existed. Name of this place means something like “god-made”. Points there was something seen extraordinary for this place possibly about its structure.
At the end Da Vinci is an engineer maybe he intentionally made background two-sided for multipe scenarious or rather ambiguous. Maybe right side represent no dam. And left side displays an empty river path and a dam.
It is important to note that it is a settlement on trade route and throughout the history it was an important place.
