Following have gone as the landmarks in the glorious history of Indian Railways..
1843: Lord Dalhousie conceived the possibility of connecting INDIA by means of Railway Communication.
1844: First proposal for the construction of Railways.
1847: Lord Dalhousie appointed as Governer-General of India.
1849: Agreement made for setting up experimental line by EIR and GIPR in Calcutta and Bombay respectively.
1850: "The Battle of Guages" was settled and standard guage of 5' 6" adopted.
1851-52: First Steam Locomotive in India "Thomason" (Guage 4' 8.1/2") and "Lord Falkland" First Broad Guage (5' 6") steam locomotive arrived.
1853: First Train, Broad Guage (5' 6") started on 16/04/1853 in Bombay from Bori Bunder to Thane.
1854: First run in Calcutta area from Howrah to Hooghly.
1855: Fairy Queen Steam Engine came in service.
1856: First run in Madras area from Veyasarpaudy to Walajah Raod (Arcot).
1856-65: First Ghats-The challenging construction of Bhor & Thul Ghats including Tunnels.
1863: Ramgotti Steam engine worked on Nalhati Railway of 4' Guage line in EIR
1866-72: Calcutta linked with Delhi, Amritsar and Bombay. Bombay linked with Madras, Cochin etc.JAMALPUR workshop in East and PAREL Workshop in West set up for maintenance of rolling stock etc.
1870: First Native-State Railway-Khamgaon.
1873: First Metre Guage line opened from Delhi to Farukhnagar.
1873: First Narrow Guage 2' 6" line started by Gaekwar Baroda State Railways.
1874-79: Railways supplied food and water in affected areas during dreaded famine.
1881: First Hill Railway ( DHR narrow Guage-2' ) towards Darjeeling opened.
1887: One of the most beautiful Station/Office building of the World Bombay V.T. constructed.
1907: "Zero" Guage (Mono-Rail-PSMT) of Maharaja Patiala started and it still works in Delhi at National Rail Museum.
1925: First Electric Train introduced by GIPR.Railway Finance seperated from General Finance for strengthening the Organisation.
1945: First Diesel Engine introduced by EIR.
1947-51: Formation of Indian Railways and then its division into Zonal Railways.
1971: Foundation stone of National Rail Museum, Delhi was laid by Hon'ble President Sh. V.V. Giri opened the National Rail Museum for Public on 1st of February. Museum is of international fame for Preservation and Promotion of Heritage Tourism, Education and Entertainment.
1984: Introduction of First Metro Rail in Calcutta.
1998: Guiness certificate for being the oldest working Steam Locomotive was granted to Fairy Queen.
1999: First Hill Railway ( DHR narrow Guage-2' ) towards Darjeeling declared as World Heritage Site by UNESCO.
1999: Name of Delhi Main Station included in Guinness Book of World Records as it has the world's largest Route Relay Interlocking system, with 11000 Relays allowing upto 1,122 signalled movements, installed by Northern Indian Railways
(Source: Official Indian Railway site)