It has two stations, connecting the quarters of Karaköy and Beyoğlu. Its tunnel goes uphill from close to sea level and is about 573 metres (1,880 feet) long.[1] Inaugurated on January 17, 1875,[1] the Tünel is the second-oldest extant subterranean urban rail line in the world, after the London Underground (1863). It is thus the oldest surviving underground urban rail line in continental Europe, as the older 1862 funicular line in Lyon has been converted into an underground road tunnel.