This is the top of an Armenian Church in Üşküdar. I have visited at one time, but in December 2015 found it closed, so I only took pictures of its top. I hope to reunite these with earlier pictures.

I found some more text on the web: "Although the construction date of the Surp Garabed Church, one of the oldest Armenian churches in Istanbul, which is located in the Murat Reis Neighbourhood in Üsküdar, is not clear, it is known that it has existed at least since the year 1555. The church was constructed as a wooden, small temple upon the firman of the sultan for Armenian workers the majority of which had migrated from Muş or Van to work in the construction of many public buildings, the Mihrimah Sultan Mosque first and foremost among them. The church has been rebuilt several times following fires, and the current church was built in stone following the great Yenimahalle Fire in 1888, and is still active today"