Workers are walking in underground tunnels during the construction of the Delhi metro subway train in India Stock Photo - Alamy
Delhi Metro | Reuters.com
Delhi Metro - Wikipedia
India's first underground metro. - Review of Metro Railway, Kolkata (Calcutta), India - Tripadvisor
List of metro systems - Wikipedia
Mumbai Metro: Inside the first underground train of this overcrowded city | Business Standard News
Does any Indian city has underground metro rail system? If not, why? - Quora
Indian Metro Rail Networks: Quick Guide, Routes Map, Start Date
India's Longest Underground Tunnels of Metro Lines
Eight firms bid for ₹1,250 crore underground construction contract for Kanpur Metro | Urban Transport News
Urban rail transit in India - Wikipedia
Kolkata first underground metro station 25 years | India News – India TV
India's first underwater Metro line in Kolkata: A look at newly opened station | Mint
Kolkata All Set For India's First Underwater Metro Services | Good News Today - YouTube
Underground or Elevated Metro Rail – Which one is better for India?
World Class Mumbai Underground Metro - An engineering wonder - YouTube
Infra Watch: Pune metro rail completes underground tunnel across Mutha river | Cities News,The Indian Express
Pune Metro completes underwater tunnel below Mutha River | Urban Transport News
East West Corridor Kolkata Metro underwater train Kolkata Metro: India's first under-water train to run between Salt Lake & Yuva Bharati Krirangan from Feb 13 | India News
Underground metro station under construction in Mumbai,India : r/InfrastructurePorn
Building a Subway in One of the World's Most Crowded Cities
