After the Revolt of 1857, the British started to build the city of New Delhi, and Shahjahanabad fell under neglect. The famous canals, wells and drainage systems got damaged during the 19th century.
The end of the 19th century also saw the decline of many havelis, which were splendid mansions where the Mughal aristocrats lived during the 17th and the 18th centuries. The British rule was making it difficult for the rich Mughals to maintain the havelis, and so, many of them were subdivided and sold off.
While the rich Mughals stayed in havelis, the British stayed in colonial bungalows meant just for one nuclear family. These bungalows were huge, single-storied constructions with inclined roofs and set in an open ground.
In 1888 Robert Clarke planned an extension scheme, called the Lahore Gate Improvement scheme to decongest the walled city. However, the scheme remained incomplete. In 1936, Delhi Improvement Trust was established. A census conducted in 1931 revealed that Shahjahanabad was horribly crowded.
The partition of India in 1947 led to a large number of people crossing the new border on both the sides increasing the population of Delhi. Streams of Muslims from Delhi left for Pakistan, and an equal number of Hindu and Sikh refugees arrived in Delhi from Pakistan.
Many new colonies, schools, colleges and shops also came up in the city during this time. The city of old Delhi saw a marked change during the 19th and the 20th centuries. The social environment of Delhi changed with the arrival of new migrants, and the Urdu culture, which was once prevalent, was replaced by new tastes in dress, food and the arts.