<Li> Salt Lake City - Ramrajatala (Presently truncated till Howrah Maidan, proposed to be expanded to Santragachi Bus Terminus) </Li> <Li> Dakshineshwar - Thakurpukur (route changed to Joka - BBD Bagh and Noapara - Dakhineshwar) </Li> <P> Of these, the highest priority was given to the busy north - south axis between Dum Dum and Tollygunge over a length of 16.45 km, and the work on this project was sanctioned on 1 June 1972 . The foundation stone of the project was laid by Indira Gandhi, the Prime Minister of India, on 29 December 1972 and the construction work started in 1973 - 74 . In those early days of Kolkata Metro, the planning, thought processing, and political facilitation of the whole project was borne almost single - handedly by the then Union Railway Minister from West Bengal - A.B.A. Ghani Khan Choudhury - often against (and to the chagrin of) the prevailing socio - political stance of his contemporaries in the West Bengal government . From the start of construction, the project had to contend with several problems including insufficient funds (until 1977 - 78), a shifting of underground utilities, court injunctions, and an irregular supply of vital materials . Despite the difficulties faced, services began on 24 October 1984, with the commissioning of a partial commercial service covering a distance of 3.40 km with five stations served in between Esplanade and Bhowanipur (currently Netaji Bhavan). The first metro was driven by Tapan Kumar Nath and Sanjoy Sil . The service was quickly followed by commuter services on another 2.15 km stretch in the north between Dum Dum and Belgachhia on 12 November 1984 . The commuter service was extended up to Tollygunge on 29 April 1986 covering a further distance of 4.24 km making the service available over a distance of 9.79 km and covering 11 stations . However, the services on the north section were suspended with effect from 26 October 1992, as this isolated small section was little used . After a gap of more than eight years, the 1.62 km Belgachhia - Shyambazaar section, along with the Dum Dum - Belgachhia stretch, was opened on 13 August 1994 . Another 0.71 km stretch from Esplanade to Chandni Chowk was commissioned shortly afterwards, on 2 October 1994 . The Shyambazaar - Shobhabazar - Girish Park (1.93 km) and Chandni Chowk - Central (0.60 km) sections were opened on 19 February 1995 . Services on the entire stretch of the Metro were introduced from 27 September 1995 by bridging the vital gap of 1.80 km in the middle . </P> <P> In the final stage, the extension of Line 1 to an elevated corridor from Tollygunge to New Garia was constructed and opened in two phases, Mahanayak Uttam Kumar to Kavi Nazrul in 2009 and Kavi Nazrul to Kavi Subhash in 2010 . The latest extension constructed was the 2.59 km elevated corridor from Dum Dum to Noapara on 10 July 2013 . </P>

Which is the first underground railway in india