This post explains the development of Delhi's "urban villages" over the past few decades, and is a supplement to the Back to Dilli Darshaning post below.
To understand the idea of the urban village in Delhi, a short primer on the history of Delhi is in order. Some of you might have heard/read this stuff before at various venues, but I love to tell this tale, so here goes!
Unlike many other old cities, Delhi's history is not one of outward growth from a single urban center. Since the 10th/11th c., different rulers shifted the urban/population center from one location to another within the expanse of land known as Delhi, creating new townships, forts, palaces and capitals in the process. In fact during the previous IASTE I speculated on how the new capital was always given a new name (Siri, Jahanpanah, Firozabad, Dinpanah, Shahjahanabad etc etc) and the old location then became known as simply "Dilli" (Delhi). The British both formalized this tradition and broke the cycle by naming their new city New Delhi and the old one (Shahjahanabad) Old Delhi.
In any case, what this lead to was the constant shifting of the urban center, leaving in it's wake various built-up locations throughout the area with greatly reduced populations. Over time these locations saw rising and falling fortunes, sometimes becoming urban centers once again and sometimes being completely abandoned. Add to this the fact that Delhi became a necropolis with the tombs of numerous rulers and saints strewn about. If the ruler or saint was popular, a settlement would arise around his (sometimes her) tomb/shrine. Overwhelmingly, this was the case with regard to saints rather than rulers.
As a result, but the time independence from the British came in 1947, there were various urban and sub-urban settlements, strewn all over the landscape. At that time, the main urban and population centers included British New Delhi, Old Delhi (Shahjahanabad) to the north of it, Civil Lines further north, the Sadar Bazaar area to the west of Old Delhi, and the new British cantonment at Dhaula Kuan. Immediately after independence, Delhi began expanding explosively in all directions from this core.
This explosive growth started consuming the smaller settlements that lay in the land surrounding the now ever expanding city. Delhi's planners were in a dilemma as to what course of action to take vis-a-vis these settlements. Should they tear them down, thus necessitating the expulsion and rehabilitation of their residents, or should they let them be as-is within the planned growth of the city. With a few exceptions, they chose the later tact, and gave special status to these "urban villages". Thus, these areas are now "islands" within the planned nature of Delhi, have their own zoning laws etc, and their own characteristics, mostly with dense haphazard streets and dense built fabric.
Due to ever increasing real estate pressures, these urban villages are becoming denser, more populated and more built up, thus the threat posed to the "historic" buildings that so often exist within them, and are so often intrinsic to the reason why the settlements exist where they do in the first place!