The National Speed Skating Oval, known as the "Ice Ribbon," is a landmark building of the 2022 Beijing Winter Olympics. In this episode of Green Front, CGTN's Kate Kui interviewed its principal architect Zheng Fang, and talked about inspirations, sustainable design and legacies to leave behind in architecture. Zheng also led the design of the Beijing National Aquatics Center, or the "Water Cube," in 2008. In his view, the greatest designs are always the simplest.