Delhi

Delhi is the capital of India and with 26 million inhabitants in the metropolitan area, also its largest city. Delhi lies in the plains of norther India, at the foot of the Himalaya mountain range.
The area of Delhi has been continuosly inhabited since the 6th century BC, although it's likely it was already settled before the second millenium BC. The earliest ruins date back to the 3rd century BC. Between 1206 and 1526 the Delhi sultanate ruled over large parts of the Indian subcontinent. Delhi was made the capital of British India in 1911.
Delhi is huge and full of traffic. The pollution situation has improved over the years, but the air is still far from being clean.
Delhi has a number of monuments and historical places, among which there are three UNESCO world heritage sites: the Qutub Minar site, Humayun's tomb and the Red Fort complex.
How to get to Delhi
Delhi has an international airport with direct flights to many countries. From within India it can also be reached by train or car/bus.
Accommodation
There are countless hotels in various parts of Delhi and its suburbs, most bookable via the international booking portals.