The Golden Quadrilateral is an initiative in India to build a highway system that links the four largest metropolises: Delhi, Mumbai, Chennai, and Kolkata. The project, which includes building and upgrading more than 5,800 km of highways, was started by the Indian government in 2001 with the goal of enhancing connectivity and infrastructure throughout the nation. The Golden Quadrilateral, India's largest highway project to date, has significantly facilitated travel, business, and trade throughout the nation.