The agglomeration of Kathmandu has not yet been officially defined. The urban area of the Kathmandu valley is split among <answer>three</answer> different districts (collections of local government units within a zone) which extend very little beyond the valley fringe, except towards the southern ranges, which have comparatively small population. They have the <answer>three</answer> highest population densities in the country. Within the districts lie VDCs (villages), 3 municipalities (Bhaktapur, Kirtipur, Madhyapur Thimi), 1 sub-metropolitan city (Lalitpur), and 1 metropolitan city (Kathmandu). Some district subdivisions remain legally villages yet are densely populated, Gonggabu VDC notably recorded a density over 20,000 people/km2. (2011 census). The following data table describes the districts considered part of the agglomeration:
How many districts make up the Kathmandu Valley urban area?
three