Introduction to Songshan Building No. 1: In June 1966, Mao Zedong inspected Shaoshan and stayed in Building No. 1 for 11 days. He wrote a letter from Wuhan on July 8 of this year, calling it "a cave in the West." In 1970, the Ouyang Hai Hero Company built a 100-meter-long air raid shelter behind the villa. On one side of the cave are military facilities such as an earthquake-proof room and a command room. At both ends of the hole, there are heavy iron doors nearly a foot thick and weighing several tons, equipped with automatic controls. Even if an atomic bomb is released outside the cave, it will not damage the command system inside the cave and the safety of the people in the cave.