This is the Koca Mustafa Paşa complex. It's mosque is a former church, St. Andrew in Krisei. Inside are some good capitals, the light was too low to take their picture.Nearby is the shrine of the famous Istanbul folk-saint Sümbül Efendi, who was the first sheik of the dervish tekke which was established here in the 16th century.
Next to the Türbe (mausoleum) of Sümbül Efendi, there is another one where Serasker (Commander in chief) Riza Paşa is buried. His cenotaph sarcophagus has been renewed recently. It is made of white marble, following a Classical Ottoman design. It is decorated with (partly painted) carved scrolls and arabesques; on top of these, Late-Ottoman calligraphic inscriptions in gilt copper were applied.
Correspondent: J.M.Criel, Antwerpen.
Source: Youtube canal of Sinaneddin Yusuf & Vikipedia.