Delhi (officially the National Capital Territory of Delhi (NCT), is a metropolitan and the capital region of India which includes the national capital city, New Delhi. It is the second most populous metropolis in India after Mumbai and the largest city in terms of area. With a population of 22 million in 2011, the city is also the fourth most populous metropolis in the world. The NCT and its urban region have been given the special status of National Capital Region (NCR) under the Constitution of India's 69th amendment act of 1991. The NCR includes the neighboring cities of Baghpat, Gurgaon, Sonepat, Faridabad, Ghaziabad, Noida, Greater Noida and other nearby towns, and has nearly 22.2 million residents. Although technically a federally administered 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 is the capital of the NCT of Delhi. Delhi has been continuously inhabited since the 6th century BC. Through most of its history, Delhi has served as a capital of various kingdoms and empires. It has been captured, sacked and rebuilt several times, particularly during the medieval period, and therefore the modern conurbation of Delhi is a cluster of a number of cities spread across the metropolitan region. Delhi is 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 during the period of the Delhi sultanates. In AD 1639, the Mughal emperor Shahjahan built a new walled city in Delhi which served as the capital of the Mughal Empire from 1649 until the Rebellion of 1857. The British captured Delhi in 1857 and the city replaced Kolkata as the seat of British government in India in 1911. A new capital city, New Delhi, was built to the south of the old city during the 1920s. When the British left India in 1947, New Delhi became the national capital and seat of government. Today Delhi contains many important historical monuments, buildings and features.