The Golden Quadrilateral (GQ) is the largest express highway project in India. It connects India's four largest metropolises: Delhi, Mumbai, Kolkata and Chennai and thus, forms a quadrilateral of sorts. Bengaluru, Pune, Ahmedabad and Surat are also served by this network. It was the first phase of the National Highways Development Project (NHDP) . It consists of 5,846km of four/six lane express highways built at a cost of ₹ 60,000 crores. The four-lane GQ highway was completed in January 2012.