Once Delhi was selected, the India Office convened a committee of experts, the Delhi Town Planning committee, which eventually included the architects Sir Edwin Lutyens and Herbert Baker, and the engineer John A. Brodie. (Sir Patrick Geddes - widely considered the intellectual father of 'regionalism' within urban planning theory and practice - suggested himself for a post; his offer was declined). Once the city and the committee were chosen, an exact site had to be identified. Lutyens argued for a site south of Shah Jahan's seventeenth century Mughal capital, on a low hill close to the village of Raisina. In a letter to the Committee, Lutyens confirmed the site's favorable "aspect, altitude, water, health, virgin soil, [and] views across old Delhi to the wilderness of ruined tombs that form the remains of the seven older Delhis." After some initial disagreement, he was successful in convincing the others. The siting of the new city assumed a growth pattern in all directions. Unlike in Bombay or Calcutta, whose physical geographies delimited urban growth, the wide expanse of developable land on all sides was considered a significant advantage. The site's spaciousness, combined with the prevailing design ethos of the day, lent itself to a decidedly suburban character: New Delhi was planned as a Beaux Arts-style Garden City, replete with extremely large building plots and wide boulevards arranged in monumental symmetry. Supposedly modeled on the Royal Crescent in Bath, England, Connaught Place remains the central business district of New Delhi and the geometric origin of a street layout that maintains powerful visual links between New Delhi and Shahjahanabad. Radial roads connect the Connaught Circus to the old city's southwestern Ajmer Gate, for example. But the axial vistas also relate the new buildings of the colonial infrastructure to existing monuments that lay outside Shahjahanabad's gates. Lutyen's grandiose Government House (Rashtrapati Bhawan) is located on Raisina Hill, and one of New Delhi's major thoroughfares, Rajpath, connects it to the Purana Qil'a (1533). Another sightline originates at Connaught Place, passes through the War Memorial Arch (or India Gate; 1921) and terminates at Humayun's mausoleum (1572), at the southeastern edge of the new city. By the time Lutyen's city was finished in 1931, India's independence, in some form or another, was imminent. 

The upheaval that accompanied Partition in 1947 included a massive evacuation of Delhi's Muslims and an even larger influx of Hindus and Sikhs. But local governance in the city did not keep pace with the rapid changes in federal governance or demographics. (A Master Plan for Delhi was not presented until 1956.) In the absence of a clear governmental infrastructure to handle the repercussions of Partition, monuments played an important role: the Purana Qil'a, for example, housed Muslim refugees until they could make safe passage to Pakistan. Other sites of Indo-Islamic significance dot New Delhi's landscape, including the Mughal tombs of Safdar Jung (1753) and the Shrine of Nizam-ud-Din Auliya (1562) that Akbar commissioned for the Sufi saint. Several tombs that fall within the new city's footprint predate the Mughal era, four of which - including the somber, octagonal Sayyid Muhammad Shah Tomb (1433) and the grand, two-storied Lodi Gardens, named after the last of the Delhi Sultans, Ibrahim Lodi. More than exclusively a funerary complex, however, the Lodi Gardens have provided an armature for the development of future generations of institutional architecture, extending well into the post-colonial era. 

The work of American architect Joseph Allen Stein added considerably to Delhi's architectural palimpsest. Many of his buildings are located within the Lodi Gardens estate: his India International Center (1959 - 1962), Ford Foundation Headquarters (1968), Ford Foundation Guest House (1972), UNICEF Headquarters (1981) and India Habitat Center (1993), contributed to the growing vocabulary of modernist design in India (Stein labeled his style 'regional modernism') by mixing local stone with concrete and Mughal-inspired grand courtyards and decorative tile flourishes with covered walkways and rational, rectilinear angles. A mix of modernist and traditionalist influences have guided New Delhi's urban development ever since. An impressive series of international embassies add to this complex architectural legacy: Satish Gujral's design for the Embassy of Belgium resembles a fortress of rocky outcrops; Inter-Consult's multi-tiered design for the Egyptian Embassy echoes the maidans of Cairo. The heart of New Delhi, as many downtowns in India, experienced a burst of utilitarian high-rise construction in the 60s and 70s. Nonetheless, Connaught Place continues to resemble many central business districts inspired by the Garden City model in its single-use, automobile-oriented, non-residential character. Outside the central circus, many of the original colonial buildings remain, as well as large pockets of Public Works Department bungalows from the 1930s. 

New Delhi has not been immune from the massive population explosion that has caused Greater Delhi to become one of the largest cities in the world, but its separate urban history and the responsibilities of being the capital of the world's largest democracy have resulted in greater planning regulation than elsewhere in the metropolitan area. As Delhi has grown to the south, west and east of New Delhi, the capital area has become the true center of a vast city-region. Contemporary architecture in New Delhi continues to reinterpret a fabric inherited from multiple empires. Raj Rewal's Parliament Library, adjacent to Lutyen's iconic Parliament House, responds to its context by synthesizing Beaux-Arts monumentalism with Mughal symmetry and the mandala-inspired layout of Hindu temple design. Charles Correa's British Council (1993) is also emblematic of New Delhi's architectural syncretism: it is set in a series of landscaped gardens and loggias, each symbolic of India's Hindu, Muslim and European past.