Glorious glaciers, boundless grasslands, thousands of lakes dotting the land like stars, and the source of many great rivers……This is Nagqu of southwest China's Xizang Autonomous Region, a place aptly known as the "roof of the world's roof." Once the only prefecture-level city in China without trees used for urban greening, Nagqu is witnessing a green miracle take root — made possible by the unwavering efforts of generations.