Azerbaijan Railways (Azerbaijani: Azərbaycan Dəmir Yolları) is the national state-owned rail transport operator in the Republic of Azerbaijan. The 2,918 km (1,813 mi), 1,520 mm (4 ft 11 27⁄32 in) gauge network is electrified at 3 kV (3,000 V) DC. The headquarters of the Azerbaijan Railways is in the capital Baku. The Azerbaijan Railways is one of the successors of the Soviet Railways, which was the successor of the Russian Imperial Railways. The first railway line in Azerbaijan was laid in 1878 and was opened in 1880 in the suburbs outside Baku.