The Line 1, Blue Line, also known as North–South Metro of the Kolkata Metro, is a rapid transit system serving Kolkata in Indian state of West Bengal. It consists of 26 operational stations from Dakshineswar to Kavi Subhash. Nine of the stations are elevated, 2 at-grade and the remaining 15 are underground, with a total distance of 32.13 km (19.96 mi). The line connects Dakshineswar and New Garia and uses 5 ft 6 in broad gauge rolling stock. Dakshineswar was opened on 22 February 2021 is an elevated station located 4.1 km (2.5 mi) north of Noapara. It was the first underground railway to be built in India, with the first operations commencing in October 1984 and the full stretch that was initially planned being operational by February 1995. On 28 December 2010, it became the 17th zone of the Indian Railways. Being the country's first, and a completely indigenous process, the construction of the Kolkata Metro was more of a trial-and-error affair, in contrast to the Delhi Metro, which has seen the involvement of numerous international consultants. As a result, it took nearly 23 years to completely construct around 15 km (9.3 mi) underground railway from Birpara up to Tollygunge Metro Station.

The Kolkata Metro is a rapid transit system serving the city of Kolkata and the wider Kolkata Metropolitan Region in West Bengal, India. Opening in 1984, it was the first operational rapid transit system in India, beside being the second busiest and fourth-longest metro network in India. As of March 2024, it has four operational lines: the 32.13 km (19.96 mi) Line 1 from Dakshineswar to Kavi Subhash, 14.1 km (8.8 mi) Line 2 from Salt Lake Sector V to Howrah Maidan, 7.75 km (4.82 mi) Line 3 from Joka to Majerhat and 5.4 km (3.4 mi) Line 6 from Kavi Subhash to Hemanta Mukherjee for a total of 59.38 km (36.90 mi). Two other lines are in various phases of construction and planning. The system has a mix of underground, at-grade and elevated stations using both broad-gauge and standard-gauge tracks. Trains operate between 06:55 and 22:30 IST and the fares range from ₹5 to ₹50.