Tehran is the capital of Iran, in Tehran Province of the country. The capital got around 16 million in the area, with 9 million living in the capital itself.

Metro of Tehran opened in 1999
Tehran, the capital of Iran, started construction of a metro system already during the reign of the Shah, but due to financing problems the first mass transit line could not open until March 1999. Now the city got 5 metro lines (that includes a airport line).

New station opened on Saturday 4th of February
It’s quite impressive to see 5 lines be built within 18 years time and now Heravi station on Line 3 opened on 4th of February 2017.

Source
Urbanrail.net
Wikipedia