Kolkata formerly Calcutta is the capital of the Indian state of West Bengal. Located on the east bank of the Hooghly River, it is the principal commercial, cultural, and educational centre of East India, while the Port of Kolkata is India’s oldest operating port and its sole major riverine port. As of 2011, the city had 4.5 million residents; the urban agglomeration, which comprises the city and its suburbs, was home to approximately 14.1 million, making it the third-most populous metropolitan area in India. As of 2008, its gross domestic product (adjusted for purchasing power parity) was estimated to be US$104 billion, which would be third highest among Indian cities, behind Mumbai and Delhi. As a growing metropolitan city in a developing country, Kolkata confronts substantial urban pollution, traffic congestion, poverty, overpopulation, and other logistic and socioeconomic problems.
The discovery and archaeological study of Chandraketugarh, 35 kilometres (22 mi) north of Kolkata, provide evidence that the region in which the city stands has been inhabited for over two millennia. Kolkata’s recorded history began in 1690 with the arrival of the English East India Company, which was consolidating its trade business in Bengal. Job Charnock, an administrator who worked for the Company, was formerly credited as the founder of the city; In response to a public petition, the Calcutta High Court ruled in 2003 that the city does not have a founder. The area occupied by the present-day city encompassed three villages: Kalikata, Gobindapur, and Sutanuti. Kalikata was a fishing village; Sutanuti was a riverside weavers’ village. They were part of an estate belonging to the Mughal emperor; the jagirdari (a land grant bestowed by a king on his noblemen) taxation rights to the villages were held by the Sabarna Roy Choudhury family of landowners, or zamindars. These rights were transferred to the East India Company in 1698.
Kolkata is subject to a tropical wet-and-dry climate that is designated Aw under the Köppen climate classification. According to a United Nations Development Programme report, its wind and cyclone zone is “very high damage risk”.
The annual mean temperature is 26.8 °C (80.2 °F); monthly mean temperatures are 19–30 °C (66–86 °F). Summers (March–June) are hot and humid, with temperatures in the low 30s Celsius; during dry spells, maximum temperatures often exceed 40 °C (104 °F) in May and June. Winter lasts for roughly two-and-a-half months, with seasonal lows dipping to 9–11 °C (48–52 °F) in December and January. May is the hottest month, with daily temperatures ranging from 27–37 °C (81–99 °F); January, the coldest month, has temperatures varying from 12–23 °C (54–73 °F). The highest recorded temperature is 43.9 °C (111.0 °F), and the lowest is 5 °C (41 °F). The winter is mild and very comfortable weather pertains over the city throughout this season. Often, in April–June, the city is struck by heavy rains or dusty squalls that are followed by thunderstorms or hailstorms, bringing cooling relief from the prevailing humidity. These thunderstorms are convective in nature, and are known locally as kal bôishakhi, or “Nor’westers” in English.
Pollution is a major concern in Kolkata. As of 2008, sulphur dioxide and nitrogen dioxide annual concentration were within the national ambient air quality standards of India, but respirable suspended particulate matter levels were high, and on an increasing trend for five consecutive years, causing smog and haze. Severe air pollution in the city has caused a rise in pollution-related respiratory ailments, such as lung cancer.
Public transport is provided by the Kolkata Suburban Railway, the Kolkata Metro, trams, and buses. The suburban rail network reaches the city’s distant suburbs. According to a 2013 survey conducted by International Association of Public Transport, Kolkata ranks the top among the six cities surveyed in India, in terms of public transport system. The Kolkata Metro, in operation since 1984, is the oldest underground mass transit system in India. It spans the north–south length of the city and covers a distance of 25.1 km (16 mi).As of 2009, five Metro rail lines were under construction. Kolkata has four long-distance railway stations, located at Howrah (the largest railway complex in India), Sealdah, Chitpur and Shalimar, which connect Kolkata by rail to most cities in West Bengal and to other major cities in India. The city serves as the headquarters of three railway Zone out of Seventeen of the Indian Railways regional divisions—the Kolkata Metro Railways, Eastern Railway and the South-Eastern Railway.