I wonder where in serkeci she was seen? Oh how that place relates to where she was found. She was kind of found in no mans land. Lots of cars driving by. But the other side of the wall is topkapi sarayi. And if I'm seeing the map right it would have been behind the buildings that house artifacts. There is a cafe just before this part. But there would have been no houses no people, as the museum can't be accessed except by the front entrance, so there would have been nothing in between topkapi and the well accept trees.
She was on her way to meet someone OR she was going to photograph graffiti (as she has in NYC and Amsterdam) because she heard, read, or was told it was there.
Given her interests, her presence in the area is understandable.