At 28.38 N latitude and 77.12 E longitude Delhi is situated in north India and stands on the west bank of Yamuna river which has witnessed the glory and the tumultuous history of the 3000 year old Delhi. Delhi is spread over an area of 1483 sq. kilometers, 216 meters above sea level and has a population of around 14 million.

Delhi is divided into several parts, but broadly can be classified as Old Delhi & New Delhi.

Old Delhi (Shahjahanabad)

'Old' Delhi, the capital of Muslim India between the mid-17th and late 19th centuries, is full of formidable mosques, monuments and forts. The ancient Delhi of the Mughal emperors was surrounded by a wall and was a congested city of narrow bylanes. Though better known as Old Delhi, this area is also called Delhi. Old Delhi , Shah Jahan's seventeenth-century capital ( Shahjahanabad ), lies 2km or so further north.The Delhi Jn rly stn is in Old Delhi, the inter-state bus terminus is slightly to the north, at the Kashmiri Gate. Buses go to all over north and west India from the Kashmiri Gate. Near the Delhi Gate lies the Yamuna on the left and the Aruna Asaf Ali Rd on the right, ending at Ramlila Pavilion, the juncture of Old and New Delhi.

It's a lively area of colourful bazaars, narrow streets and barely controlled chaos. Monuments in sandstone and marble, which stand in assorted states of repair, make Delhi a veritable museum of Indo-Islamic architecture, seen at its best in the frenetic streets of Old Delhi. Old Delhi looks entirely different from the more modern New Delhi and south Delhi areas.

New Delhi

The other Delhi, the imperial city created as the capital of India by the British. In addition to its historic interest and role as the government centre, Delhi is a major travel gateway. In 1911, the British asked Lutyens to give new meaning to city development which is reflected in the architectural designs and sophistication that buildings in Delhi like Parliament House, Rashtrapati Bhavan, India Gate, Connaught Place and various administrative buildings like the South and North blocks along the breathtaking view available from Raj Path. The capital of the Indian republic is at New Delhi, the planned city devised by the British. The smooth roads, modern houses and buildings and offices and departments attract tourist. As you come out of the New Delhi rly stn, in front is Paharganj and on the south Chemsford Road which intersect at Connaught Place. New Delhi, the imperial city created by the British Raj, is composed of spacious, tree-lined avenues and imposing government buildings, and has a sense of order absent from other parts of the city.

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Central New Delhi

The hub of the metropolis is Central New Delhi, an orderly plan of wide roads lined with sturdy colonial buildings which was established soon after the imperial capital of British India moved here in 1911. At its hub, the royal mall, Rajpath, runs from palatial Rashtrapati Bhavan, in the west, to the India Gate war memorial in the east. At the north edge of the new capital lies the thriving business centre, Connaught Place, where neon advertisements for Wimpy, American Express, hotels and countless airline offices adorn the flat roofs and colonnaded verandas of high white buildings that curve around a central park to form an almost perfect circle. Most of the airline offices, travel agents, banks and hotels are here. There are a number of cinemas and performing arts centres around Connaught Place, but Delhi's strict licensing laws effectively curtail nightlife. Central New Delhi also has its fair share of more recent high-rise offices and hotels, standing close to pre-British constructions such as the open-air observatory, Jantar Mantar, and a generous smattering of excellent museums covering arts and crafts and the lives of India's post-Independence politicians.

South Delhi

Most of the early settlements of Delhi, including its first cities, are to be found not in "Old Delhi" but in SOUTH DELHI, the area south of Connaught Place and Rajpath. Although the rapid expansion of suburban Delhi is swallowing up the countryside, the area remains littered with monuments from the past, and pockets of almost untouched rural peace make it a fascinating blend of the contemporary, the pastoral and the historic.

References
http://www.mapsofindia.com/stateprofiles/delhi/index.html
http://www.whereincity.com/india/delhi/