One-function towns are a defunct term nowadays. To find a town carrying out only one function is utterly rare. People have realised the benefits that comes from diversifying their functions, these functions are often complementary and can add to the overall output of the town/city in which they live. For certain reasons, one-function may come to dominate all the other functions and often is substituted with the name of the town.

For instance, say Agra, it has a rich historical heritage but that town is known for more – leather industry. Thus, one-function towns are a thing of past. Presently, towns perform multiple functions, but one function may come to dominate the region (often a function for which has been famous for).

Cities become multi-functional as and when it grows. A small town/city often resorts to specialise in a single activity to remain relevant for the economy. But when the city grows, population increases and expands over space, it no longer can rely on the single activity to sustain itself. The city will embrace newer functions to keep it sustainable. Thus, the cities are not static in their function. The function changes due to their dynamic nature. Over time, the functions get so intertwined that the city cannot be categorised in a particular functional basis.