Tünel , the underground funicular train of Istanbul

The Tünel (English: Tunnel ) is a short underground railway line in Istanbul, Turkey. It is an underground funicular with two stations, connecting the quarters of Karaköy/Galata and Beyoğlu/Pera . Located at the northern shore of the Golden Horn, the underground railway tunnel goes uphill from close to sea level and is about 573 metres long. Inaugurated on January 17, 1875, the Tünel is the second-oldest subterranean urban rail line in the world, after the London Underground (1863), and the first subterranean urban rail line in continental Europe.