On the picture: The marble mihrab and minber, in Classical Ottoman style.

Mihrab = a semicircular niche in the wall of a mosque that indicates the direction of the Kaaba in Mecca and hence the direction that Muslims should face when praying. The wall in which a mihrab appears is the "qibla wall."
Minber = a pulpit in the mosque where the imam (prayer leader) stands to deliver sermons.

Correspondent: J.M.Criel, Antwerpen.
Source: ‘Vakıf Abideler ve eski Eserler’ - Vakıflar Genel Müdürlüğü, Ankara 1983 & Wikipedia.