On the picture: The ‘mihrab’ area of the Yıldırım Beyazıt mosque, which is the most southern room of the building; it is 11,70 x 11,70 m large.
From left to right, along the so-called ‘qibla’-wall, one sees a small ‘vaaz kürsüsü’ (= pulpit of the sermon), the ‘mihrab’ (prayer niche that indicates the direction of the Kaaba in Mecca) and the ‘minber’.
‘Minber’ and ‘vaaz kürsüsü’ are both pulpits, from where sermons are given. The difference is that the minber is obligatory for the ‘Friday sermon’, held during the most important common prayer of Islamic week. All other sermons can be held from the smaller ‘kürsü’.

The decoration of the mihrab, and the minber, date from the last quarter of the 19th century, when the mosque was restored after the 1855 Bursa earthquake. They are executed in a Classic Ottoman style, following examples of the 16th-17th century.
As to the numerous calligraphic works on the walls, they belong to the late-Ottoman 19th century.

Correspondent: J.M.Criel, Antwerpen.
Source: ‘Vakıf Abideler ve eski Eserler (volume III)’ - Vakıflar Genel Müdürlüğü, Ankara 1983 & Vikipedia.