Delhi officially the National Capital Territory of Delhi (NCT) that includes the Indian capital; is the second largest metropolis of India after Mumbai. With the population of 16.7 million in 2011, the city is the 2nd most populous metropolis in India and 8th most populous metropolis in the world. The NCT and its urban region has been given the special status of National Capital Region (NCR) under the Indian constitution's 69th amendment act of 1991. There are nearly 22.2 million residents in the greater NCR urban area, which includes the neighboring cities of Baghpat, Gurgaon, Sonepat, Faridabad, Ghaziabad, Noida and Greater Noida along with other smaller nearby towns.
Delhi is known to have been continuously inhabited since 6th century BC. Through most period of its history, Delhi has served as a capital of kingdoms and empires. It has been invaded, ransacked and rebuilt several times, particularly during the Medieval era, and therefore today's city of Delhi is a cluster of many capital cities scattered across the city's dimensions. Delhi is also widely believed to have been the site of Indraprastha (the legendary capital of the Pandavas during the times of the Mahabharata). Delhi re-emerged as a major political, cultural and commercial city along the trade routes between northwest India and the Gangetic plain after the rise of the Delhi sultanates. It houses many ancient and medieval monuments, archaeological sites and remains.
In 1639 AD, the Mughal emperor Shahjahan built a new walled city in Delhi which served as a capital of the Mughal Empire from 1649 until 1857. The British had captured Delhi by 1803 and George V announced in 1911 that the capital of British controlled parts of India would be Delhi. So a new capital city, New Delhi, was built to the south of the old city during the 1920s. When India gained independence from British rule in 1947, New Delhi was declared its capital and seat of government.
The name Delhi is often also