The province of Tehran
has nearly 15,000,000 inhabitants and is Iran
's most densely populated region. Its area is around 18,637 square kilometres. The city of Tehran
is the capital of both the province and the country, it is the central district of the province. Other districts are: Shemiranat, Rey, Islam Shahr, the city of Ray
, Karaj, Jajrood, Lar, and Rood Shoor. The province gained importance when it Tehran
was claimed the capital by the Ghajar in 1778
. Today Tehran ranks in the top 20 metropolitans of the world.