Delhi, officially the National Capital Territory (NCT) of Delhi, is a city and a union territory of India containing New Delhi, the capital of India. Straddling the Yamuna river, primarily its western or right bank, Delhi shares borders with the state of Uttar Pradesh in the east and with the state of Haryana in the remaining directions. The NCT covers an area of 1,484 square kilometres (573 sq mi). According to the 2011 census, Delhi's city proper population was over 11 million, while the NCT's population was about 16.8 million. Delhi's urban agglomeration, which includes the satellite cities of Ghaziabad, Faridabad, Gurgaon and Noida in an area known as the National Capital Region (NCR), has an estimated population of over 28 million, making it the largest metropolitan area in India and the second-largest in the world (after Tokyo).The topography of the medieval fort Purana Qila on the banks of the river Yamuna matches the literary description of the citadel Indraprastha in the Sanskrit epic Mahabharata; however, excavations in the area have revealed no signs of an ancient built environment. From the early 13th century until the mid-19th century, Delhi was the capital of two major empires, the Delhi sultanate and the Mughal Empire, which covered large parts of South Asia. All three UNESCO World Heritage Sites in the city, the Qutub Minar, Humayun's Tomb, and the Red Fort, belong to this period. Delhi was the early centre of Sufism and Qawwali music. The names of Nizamuddin Auliya and Amir Khusrau are prominently associated with it. The Khariboli dialect of Delhi was part of a linguistic development that gave rise to the literature of the Urdu language and then of Modern Standard Hindi. Major Urdu poets from Delhi include Mir Taqi Mir and Mirza Ghalib. Delhi was a major centre of the Indian Rebellion of 1857. In 1911, New Delhi, a southern region within Delhi, became the capital of the British Indian Empire. During the Partition of India in 1947, Delhi was transformed from a Mughal city to a Punjabi one, losing two-thirds of its Muslim residents, in part due to the pressure brought to bear by arriving Hindu refugees from western Punjab. After independence in 1947, New Delhi continued as the capital of the Dominion of India, and after 1950 of the Republic of India. Delhi ranks fifth among the Indian states and union territories in human development index. Delhi has the second-highest GDP per capita in India (after Goa). Although a union territory, the political administration of the NCT of Delhi today more closely resembles that of a state of India, with its own legislature, high court and an executive council of ministers headed by a Chief Minister. New Delhi is jointly administered by the federal government of India and the local government of Delhi, and serves as the capital of the nation as well as the NCT of Delhi. Delhi is also the centre of the National Capital Region, which is an "interstate regional planning" area created in 1985. Delhi hosted the inaugural 1951 Asian Games, the 1982 Asian Games, the 1983 Non-Aligned Movement summit, the 2010 Men's Hockey World Cup, the 2010 Commonwealth Games, and the 2012 BRICS summit and was one of the major host cities of the 2011 Cricket World Cup.

Faridabad () is the most populous city in the Indian state of Haryana and a part of Delhi National Capital Region. It is one of the major satellite cities around Delhi and is located 284 kilometres south of the state capital Chandigarh. The river Yamuna forms the eastern district boundary with Uttar Pradesh. The Government of India included it in the second list of Smart Cities Mission on 24 May 2016. Faridabad has been described as the eighth fastest growing city in the world and the third in India by the City Mayors Foundation survey. As per the 2001 Delhi Regional Plan, Faridabad is part of the Delhi Metropolitan Area (DMA).The newly developed residential and industrial part of Faridabad (Sec. 66 to 89) between the Agra Canal and the Yamuna River is commonly referred to as Greater Faridabad. The area is being developed as a self-sustained sub-city with wide roads, tall buildings, malls, educational institutions, and health and commercial centers. Sectors 66 to 74 are Industrial Sectors, while Sectors 75 to 89 are Residential Sectors.Faridabad is a major industrial hub of Haryana. 50% of the income tax collected in Haryana is from Faridabad and Gurgaon. Faridabad is famous for henna production from the agricultural sector, while tractors, motorcycles, switch gears, refrigerators, shoes, tyres and garments constitute its primary industrial products. In 2018, Faridabad was considered by the World Health Organization as the world's second most polluted city. In 2020, Faridabad ranked 10th in the Swachh Survekshan Survey's top ten dirtiest cities in India in 2020.Faridabad has been selected as one of the hundred Indian cities to be developed as a smart city under Government of India's flagship Smart Cities Mission by Ministry of Urban Development.