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.