This is the Yıldırım Beyazit Camii.
The 'Yıldırım Camii' is also called ‘Ulu Cami’ (Great Mosque), 'Karakadi Camii' (Mosque of the Black Judge) or 'Paşa Camii' (Mosque of the Pasha). Built in 1382, ordered by (the future sultan) Yıldırım Beyazıt, who was governor of the region at that time. The mosque has been restored several times, last after a severe earthquake in 1944. Fortunately, this didn’t alter its original appearance too much.
On the picture: The main entrance (on the left) and the western entrance (on the right).
Correspondent: J.M.Criel, Antwerpen.
Sources: ‘Vakıf Abideler ve eski Eserler’ II - Vakıflar Genel Müdürlüğü, Ankara 1977 & Personal visit (1996).