This is inside the Fatih complex: the mosque to the west, in front the gate leading to a special entrance for the sultan (I was told, don't know for certain).
Through the small gate to the left one enters the türbe part, where the first grave monument is that of Fatih Mehmet himself (there are many others).
Note the slope of the corridor, behind the ‘Sultan’s Gate’ (on the right side of the picture). This wide and rising passage (without stairs) allowed the sultan to reach the ‘Hünkâr mahfili’ (= ‘lodge of the lord’, a space reserved for the sultan or his representative) on horseback.
The Nurosmaniye mosque (at the eastern entrance to the Kapalı Çarşı/Grand Bazar), built in 1748-1755, has a similar ‘slope passage’. Ditto for the Laleli Camii (in the Laleli neighbourhood), built in 1764.
Correspondent: J.M.Criel, Antwerpen.