Delhi:2nd Most Populous City in the World.

--United Nations.

Delhi has become the world's most populous city in the world after Tokyo.More than doubling its population since 1990 to 25 million, according to a UN report.
The 2014 revision of the World Urbanisation Prospects launched on Thursday said India was projected to add the highest number of people to its urban population by

2050,ahead of China.

The Indian capital is expected to retain the spot of the World's second most populous city through atleast 2030, when its population is expected to rise swiftly to 36 million,according to the report.

Tokya topped the UN's ranking of the most populated city with 38 million inhabitants.While Tokyo's population is expected to decline by 2030 with 37 million people.Mumbai which is sixth in the list is expected to rise to fourth place, by 2030.  According to the report the most urban growth will be in India,Nigeria and China till 2050.

Kolkata,Hyderabad and Chennai are projected to be among the top 30 most populous in the world.In 1990 world had 10 megacities, which rose to 28 in 2014 and now it is projected to rise till 41 megacities in 2030.