Italian architect Stefano Boeri has unveiled plans for a "vertical forest" in China, a pair of towers covered with trees and trailing plants in the centre of Nanjing. Over 1,000 trees, 2,500 cascading plants and shrubs will line the facades of the Nanjing Vertical Forest, which is already under construction in the city's Pukou District. The mixed-used development commissioned by the state-owned National Investment Group, follows Boeri's past trials of "vertical forests" in Milan and in Lausanne. The concept aims to provide sustainable high-density housing and office space in urban areas, capable of producing oxygen through its plant-covered facades. The architect plans to roll the concept out across Chinese cities to help offset pollution.