Karachi is the country’s largest city, principal seaport and is a major commercial and industrial centre. A true world mega-city, greater Karachi is spread over an ever expanding 3500 square kilometres. If you want to make it anywhere, the saying goes, you have to head for Karachi. As a result, Karachi is one of the most diverse and cosmopolitan cities in Pakistan, with ethnic Sindhis matched by large numbers of Punjabis, Pashtuns and other nationalities. Karachi also has large Christian and Hindu communities, and is a centre for Zoroastrianism.