The Union Ministry of Housing and Urban Affairs has paired up 20 best performing smart cities with least performing cities.They will work as “sister cities”. Highlights The best performing cities include Tiruppur, Nagpur, Bhopal, Ranchi, Kanpur, Surat, Indore, Vellore, Vishakhapatnam, Varanasi, Vellore, Nashik, Vadodara, Pune, Kota, Davangere, Dehradun, Udaipur, Amaravati and Agra. The programme to join a least performing city with the best performing city has been named 20-20 formula. The sister cities under the programme will sign MoUs. For instance, Ranchi has been paired with Pune, and Shimla with Dharmsala and so on. The pairing has been done based on culture and region.