is the capital and largest city of Tamil Nadu, the southernmost state of India. It is located on the Coromandel Coast of the Bay of Bengal. As per the 2011 Indian census, Chennai is the sixth-most-populous city in India and forms the fourth-most-populous urban agglomeration. The city is coterminous with Chennai district, which together with the adjoining suburbs constitutes the Chennai Metropolitan Area, one of the largest metropolitan areas of India. It is administered by the Greater Chennai Corporation, which was incorporated in 1688, and is the second oldest municipal corporation in the world after the City of London Corporation. Being the capital of the state, it houses major government institutions including the Tamil Nadu Legislative Assembly, and the Madras High Court.
Archeological evidence points to human settlements in the region during the Stone Age. Historically, from the 1st century CE, the region was part of the Chola, Pallava, Pandya, and Vijayanagara kingdoms during various eras. In 1639 CE, the British East India Company obtained a grant for a strip of coastal land which then contained the fishing village of Madrasapattinam. The British developed the Madras port and built Fort St. George, the first British fortress in India. The British was engaged in conflict with the French for the control of the city in the 18th century. By the late 18th century, the British had conquered most of the region and established the Madras Presidency with Madras as the capital. After India gained independence in 1947, Madras became the capital city of the Madras State, the predecessor to the present-day state of Tamil Nadu. The city was officially renamed as Chennai in 1996.
Chennai lies on the predominantly flat Eastern Coastal Plains, and experiences a tropical climate with high humidity. It receives most of the rainfall from Northeast monsoon with cyclones being common features during the season, resulting in water inundation and flooding in low-lying areas. , Chennai had an estimated GDP of $143.9 billion, ranking it among the most productive metro areas in India. It has a diversified industrial base anchored by different sectors, and is amongst the top export districts in the country, with more than US$2563 billion in exports. It is ranked as a beta-level city in the Global Cities Index, and houses a major portion of India's automobile industry. The city has a well developed infrastructure, and is a major transportation hub. It is a major centre for medical tourism and is termed "India's health capital". It is ranked as the second-safest city in India by National Crime Records Bureau in 2023.
Chennai is home to a diverse population of ethno-religious communities, with a majority Hindu population (80.7%). The city houses nearly three million migrant population and has the third-largest expatriate population in India. Known as the gateway to South India, it is amongst the most-visited Indian cities by international tourists and was ranked 36th among the most-visited cities in the world in 2019 by Euromonitor. Tamil is the most widely spoken language, with Madras Bashai being a unique linguistic variation of Tamil spoken by people in the city. Chennai is a major centre for music, art and dance and is called the Cultural Capital of South India. The oldest buildings in the city date from the 6th to 8th centuries CE, and the city has buildings encompassing diverse styles of architecture developed during different time periods in history. It is a major film production centre and home to the Tamil-language film industry. In October 2017, Chennai was added to the UNESCO Creative Cities Network (UCCN) list.
Etymology
The name Chennai was derived from the name of Chennappa Nayaka, a Nayak ruler who served as a general under Venkata Raya of the Vijayanagara Empire from whom the British East India Company took the town in lease in 1639. The first official use of the name was in August 1639 in a sale deed to Francis Day of the East India Company. A land grant was given to the Chennakesava Perumal Temple in Chennapatanam later in 1646, which some scholars argue to be the first use of the name. A Vijayanagara-era inscription found in 2015 was dated to the year 1367 and mentions the port of Mādarasanpattanam, along with other small ports on the east coast, and it was theorized that the aforementioned port is the fishing port of Royapuram. Madras might have been derived from Madraspattinam, a fishing village north of Fort St. George.
In July 1996, the Government of Tamil Nadu officially changed the name from Madras to Chennai. The name "Madras" continues to be used occasionally for the city as well as for places or things named after the city in the past.
History
Stone Age implements have been found near Pallavaram in Chennai, and according to the Archaeological Survey of India, Pallavaram was a megalithic cultural establishment, with evidence of pre-historic settlements. The region around Chennai was an important administrative, military, and economic centre for many centuries. During the 1st century CE, Tamil poet Thiruvalluvar lived in the town of Mylapore, a neighbourhood of present-day Chennai. In the 2nd century CE, the region was part of Tondaimandalam ruled by the Early Cholas, who subdued the Kurumbas, the original inhabitants of the region. The Pallavas of Kanchi became the independent rulers of the region from 3rd to 9th century CE, and the areas of Mahabalipuram and Pallavaram were developed during the reign of Pallava king Mahendravarman I. In 879 CE, the Pallavas were defeated by the Later Cholas led by Aditya I. Jatavarman Sundara Pandyan later brought the region under the Pandya rule in 1264 CE.
thumb|left|18th-century print of Fort St. George, the oldest English settlement in India
The Portuguese arrived in 1522 CE and built the port of São Tomé, named after the Christian apostle St. Thomas, who is believed to have preached in the area between 52 and 70 CE. In 1612, the Dutch established themselves near Pulicat to the north of Chennai. On 20 August 1639, Francis Day of the British East India Company, along with the Chennapa Nayaka, the Nayak of Kalahasti, met with the Vijayanagara emperor Peda Venkata Raya at Chandragiri and requested a grant for land on the Coromandel coast on which the company would build a factory and warehouse for their trading activities. On 22 August 1639, a grant was given for a strip of land about long and inland for an annual sum of fifty million pagodas. The land was then part of a fishing village known as Madraspatnam.
thumb|upright=0.9|Map of Madras,
In 1746, during the Battle of Madras, the city along with the Fort St. George, was captured and plundered by the French under the command of General La Bourdonnais, then Governor of Mauritius. The British resisted a French siege attempt in 1759. In 1769, the city was threatened by Hyder Ali during the First Anglo-Mysore War and the Treaty of Madras later ended the conflict. By the 18th century CE, the British had conquered most of the region and established the Madras Presidency with Madras as the capital.
Madras became a major naval base and the central administrative centre for the British in South India. The city was the baseline for the Great Trigonometrical Survey of India, which was started on 10 April 1802. With the advent of railways in India in the 19th century, the city was connected to other major cities such as Bombay and Calcutta, promoting increased communication and trade with the hinterland.
After India gained its independence in 1947, the city of Madras became the capital of Madras State, the predecessor of the current state of Tamil Nadu. The city was the location of the hunger strike and death of Potti Sreeramulu, which resulted in the formation of Andhra State in 1953 and eventually the re-organization of Indian states based on linguistic boundaries in 1956.
In 1965, agitations against the imposition of Hindi and in support of continuing English as a medium of communication arose which marked a major shift in the political dynamics of the city and eventually led to English being retained as an official language of India alongside Hindi. On 17 July 1996, the city was officially renamed from Madras to Chennai, in line with then a nationwide trend for replacing anglicised names. On 26 December 2004, a tsunami lashed the shores of Chennai, killing 206 people and permanently altering the city's coastline. The 2015 Chennai Floods submerged major portions of the city, resulting in the deaths of 269 people and damages of .
Environment
Geography
thumb|Satellite image of Chennai
Chennai is located on the southeastern coast of India and northeastern part of Tamil Nadu. It lies on a flat coastal plain known as the Eastern Coastal Plains, with an average elevation of and highest point at . The geology consists of mostly clay soil, with shale and sandstone rocks. Clay underlies most of the city with sandy areas found along the river banks and coasts where rainwater runoff percolates quickly through the soil. Certain areas in South Chennai have a hard rock surface. As of 2018, the city had a green cover of 14.9 per cent, and a per capita green cover of against the World Health Organization recommendation of .
, water bodies covered an estimated area of the city. Two major rivers flow through Chennai, the Cooum River through the centre and the Adyar River to the south. A section of the Buckingham Canal built in 1877–78, runs parallel to the Bay of Bengal coast, linking the two rivers. Kosasthalaiyar River traverses through the northern fringes of the city before draining into the Bay of Bengal, at Ennore Creek. The Otteri Nullah, an east–west stream, runs through north Chennai and meets the Buckingham Canal at Basin Bridge. The groundwater table in Chennai is at below ground level on average and is replenished mainly by rainwater. The city has a coastline, of which experiences erosion, with sand accretion along the shoreline at the Marina beach and the area between the Ennore Port and Kosasthalaiyar.
Geology
Chennai is situated in Seismic Zone III, indicating a moderate risk of damage from earthquakes. Owing to the tectonic zone the city falls in, the city is considered a potential geothermal energy site. The crust has old granite rocks dating back nearly a billion years indicating volcanic activities in the past with expected temperatures of at depth.
Climate
Under the Köppen climate classification, Chennai has the dry-summer version of a tropical savanna climate (As), closely bordering the dry-winter version (Aw) due to a February average rainfall of . The city lies on the thermal equator and as it is also located on the coast, there is no extreme variation in seasonal temperature. The hottest time of the year is from April to June with an average temperature of . The highest recorded temperature was on 31 May 2003. The coldest time of the year is in DecemberJanuary, with average temperature of and the lowest recorded temperature of on 11 December 1895 and 29 January 1905.
Chennai receives most of its rainfall from the northeast monsoon between October and December while smaller amounts of rain also come from the southwest monsoon between June and September. The dry season is between January and May, with March having the least average rainfall at . The average annual rainfall is about . The highest annual rainfall recorded was in 2005. Prevailing winds in Chennai are usually southwesterly between April and October and northeasterly during the rest of the year. The city relies on the annual monsoon rains to replenish water reservoirs. Cyclones and depressions are common features during the season. Water inundation and flooding happen in low-lying areas during the season with significant flooding in 2015 and 2023.
Flora and fauna
thumb|[[Greater flamingos wintering at Mudaliarkuppam]]
A protected estuary on the Adyar River forms a natural habitat for several species of birds and animals. Chennai is also a popular city for birding with more than 130 recorded species of birds have been recorded in the city. Marshy wetlands such as Pallikaranai and inland lakes also host a number of migratory birds during the monsoon and winter. The southern stretch of Chennai's coast from Tiruvanmiyur to Neelangarai are favoured by the endangered olive ridley sea turtles to lay eggs every winter. Guindy National Park is a protected area within the city limits and wildlife conservation and research activities take place at Arignar Anna Zoological Park. Madras Crocodile Bank Trust is a herpetology research station, located south of Chennai. The city's tree cover is estimated to be around with 121 recorded species belonging to 94 genera and 42 families. Major species include Copper pod, Indian beech, Gulmohar, Raintree, Neem, and Tropical Almond. The city's marine and inland water bodies house a number of fresh water and salt water fishes, and marine organisms.
Environmental issues
thumb|[[Chitlapakkam Lake in the southern part of the city]]
Chennai had many lakes spread across the city, but urbanization has led to the shrinkage of water bodies and wetlands. The water bodies have shrunk from an estimated in 1893 to in 2017. Nearly half of the native plant species in the city's wetlands have disappeared with only 25 per cent of the erstwhile area covered with aquatic plants still viable. The major water bodies including the Adyar, Cooum and Kosathaliyar rivers, and the Buckingham canal are heavily polluted with effluents and waste from domestic and commercial sources.
The Chennai River Restoration Trust set up by the government of Tamil Nadu is working on the restoration of the Adyar River. The Environmentalist Foundation of India is a volunteering group working towards wildlife conservation and habitat restoration.