This is the Yıldız Hamidiye Mosque, built on the orders of Abdülhamid II (1842-1918, reigned 1876-1909). It was constructed in 1884-1886, architect Sarkis Balyan.
The Balyan family (Armenian: Պալեաններ) was a Armenian dynasty of famous Ottoman Imperial architects. For five generations in the 18th and 19th centuries, they designed and constructed numerous major buildings, including palaces, kiosks, mosques, churches, and various public buildings, mostly in Constantinople, present-day Istanbul. The nine well-known members of the family served six sultans in the course of almost a century and were responsible for the westernization of the architecture of the then-capital.
Sarkis Balyan (1835–1899) was part of the fourth generation; amongst his most notable works one can mention (amongst many others): the Beylerbeyi Palace (with his father Garabet Balyan), the Malta Pavilion (in the garden of Yıldız Palace), the Çırağan Palace, the Pertevniyal Valide Sultan Camii in the Aksaray district of Istanbul (with his brother Hagop Balyan), the Dolmabahçe Clock Tower.
Correspondent: J.M.Criel, Antwerpen. Sources: Website of ‘ibb.gov.tr’ & Vikipedia/Wikipedia.