A view of Unit 731 site. A strong sense of depression can be easily felt. [Photo by He Keyao/chinadaily.com.cn]

The museum built on the site of Japanese Unit 731 is seeing tens of thousands visitors as the 70th anniversary of end of WWII approaches. The site is by far the largest historical monument to biological warfare in world war history. Evidence of Japanese crimes against humanity is on display.

Unit 731 was a secret military medical force that conducted biological and bacterial warfare research in China during the Japanese aggression in WWII. Based in Pingfang district, Harbin city, the unit carried out a wide range of experiments, from chemical and biological warfare tests on live humans to vivisections.

Around 3,000 to 12,000 people, including women, children and even infants, died during the experiments conducted by the unit from the mid 1930s until 1945,according to incomplete record.