sentences:  The DDA master plan was revised in 1982 to formulate the Master Plan 2001 and then re-revised in 2007 to form the Delhi Master Plan 2021.It lays down the basic infrastructure requirements for a city estimated to have a population of 128 lakhs (12.8 million).The development of housing projects by DDA commenced in 1967 with the construction of houses and providing the basic amenities like electricity, water supply, sewage disposal, and other infrastructure facilities.