@Babur
According to wikipedia Karachi is already twin cities with
Port Louis, Mauritius since May 1, 2007
Kolkata, India
Shanghai, China
Hong Kong
Jeddah, Saudi Arabia
Tashkent, Uzbekistan
Istanbul, Turkey
Beirut, Lebanon
Dhaka, Bangladesh
Chicago, United States
Izmir, Turkey, since 1985
Houston, United States