Edirne , historically known as Adrianople, is a city in the northwestern Turkish province of Edirne, in the region of East Thrace, close to Turkey's borders with Greece and Bulgaria. Edirne served as the third capital city of the Ottoman Empire from 1363 to 1453, before Constantinople (present-day Istanbul) became the empire's fourth and final capital. At present, Edirne is the capital of Edirne Province in Turkish Thrace. The city's estimated population in 2014 was 165,979.