Haydarpaşa Terminal in the context of "Karaköy"

The Hejaz railway (also spelled Hedjaz or Hijaz; Arabic: سِكَّة حَدِيد الحِجَاز sikkat ḥadīd al-ḥijāz or Arabic: الخَط الحَدِيدِي الحِجَازِي, Ottoman Turkish: حجاز دمیریولی, Turkish: Hicaz Demiryolu) was a narrow-gauge railway (1,050 mm / 3 ft 5+11⁄32 in track gauge) that ran from Damascus to Medina, through the Hejaz region of modern-day Saudi Arabia, with a branch line to Haifa on the Mediterranean Sea. The project was ordered by Sultan Abdul Hamid II in March 1900.

It was a part of the Ottoman railway network and the original goal was to extend the line from the Haydarpaşa Terminal in Kadıköy, Istanbul beyond Damascus to the Islamic holy city of Mecca. However, construction was interrupted due to the outbreak of World War I, and it reached only to Medina, 400 kilometres (250 mi) short of Mecca. The completed Damascus to Medina section was 1,300 kilometres (810 mi). It was the only railway completely built and operated by the Ottoman Empire.

Kadıköy (Turkish pronunciation: [kaˈdɯkøj] ) is a municipality and district in Istanbul Province, Turkey. Its area is 25 km, and its population is 467,919 (2023). It is a large and populous area in the Asian side of Istanbul, on the northern shore of the Sea of Marmara. It partially faces the historic city centre of Fatih on the European side of the Bosporus. It is bordered by the districts of Üsküdar, to the northwest, Ataşehir, to the northeast, and Maltepe, to the southeast.

Kadıköy was known in classical antiquity and during the Roman and Byzantine eras as Chalcedon (Greek: Χαλκηδών). Chalcedon was known as the 'city of the blind'. The settlement has been under control of many empires, finally being taken by the Ottomans before the fall of Constantinople. At first, Chalcedon was rural, but with time it urbanized. Kadıköy separated from the Üsküdar district in 1928.