Mixed Landuse is usually a consequence of landuse planning.
Landuse planning is the process by which different areas on a piece of land are assigned for different landuses.
Cities and Towns are planned based on zones which each zones have different function. For example: industrial, commercial, housing or leisure.
People have to travel over long distances to get from one zone to another. In order to allow them to travel form zone to zone, countries are starting to develop mixed landuse project. Mixed landuse projects involve combination of shopping malls , offices, houses and hotels in one area. Some landuses are closely packed in a small area and connect pestrian walkways and escalators.
Nowadays, mixed landuse projects are developing on a small scale in many cities such as London and Singapore, usually on areas of a few hectares.