Perhaps it has some historical role and value for the Turks. For tourists, it is incomprehensible, abandoned or simply closed and has not been used for a long time. It is convenient to make an appointment - one in the middle of the site stands in front of the Topkapi entrance.
I looked at the building, well, it's historic, but I didn't see a fountain. It is necessary to visit with guides, maybe they will tell you something amazing.