1860 “Underwater Steel Tunnel”: The idea of joining Anatolia (Asia) and Rumelia (Europe) railways with a tunnel underneath the Bosphorus was first proposed in 1860’s. Bosphorus Tunnel Project prepared by French engineer S. Preault was not possible to carry out with the times technological opportunities.

1902 “Tünel-I Bahri”: The Transition project came up in Sultan II. Abdulhamit’s Period in 1902. American engineers prepared a new metro project. The project, consisted of operating a train with three wagons, two for carrying passenger and one for carrying luggage.

2005 “Marmaray”: Marmaray Railway Project was planned in a way to create the east-west transportation corridor of Istanbul. Marmaray which will start from Gebze in the Anatolian side to Halkalı in the European side aims to provide a continuous railroad journey for 76 kilometers. The biggest achievement of this project is 3,2 kilometer long tunnel passing underneath the Bosphorus. Marmaray in 54 meter depth, outscored Bart Tunnel in San Francisco with 15 meter difference and became world’s deepest immersed tunnel.

2013 ”Marmaray” : An historic expedition: After the ceremony arranged in Üsküdar Square, Marmaray’s first trip took place. Yenikapı Station situated in the historical pattern was put into service.