Photo taken on April 9, 2015 shows building remains at the preliminarily cleaned core area of the site of the Japanese Unit 731 troop in Harbin, capital of northeast China's Heilongjiang province. Unit 731 was a biological and chemical warfare troop set up in China by the Japanese invaders during World War II. The clearing process in the Unit 731 site's core area, which consists of a bacteria lab and a prison used to keep people for biological experiments, will be open to the public around the 70th anniversary of China's victory in World War II and the Chinese People's War of Resistance Against Japanese Aggressions this year. (Photo: Xinhua/Wang Jianwei)
