HARBIN - China began to renovate the former headquarters site of the notorious Japanese army unit 731 in the northeastern city of Harbin on Wednesday.

Unspeakable cruelty of wartime Japan

The renovation will last until Aug. 30 next year. Most parts of the building, now the Museum of Evidence of War Crimes by Japanese Army Unit 731, will be closed except for a special exhibition and an outdoor area.

The project aims to not only renovate the museum but also coincides with the 70th victory anniversary of China's anti-Japanese war as well as the World Anti-fascist War next year.

The museum staff did not reveal the investment of the project.

The 6,300-square-meter building is home to 13 exhibition rooms, a gallery and an exhibition hall. It has received more than 400,000 visitors this year.

Unit 731 was a top-secret biological and chemical warfare research base established in Harbin in 1935 as the center of Japan's biological warfare in China and Southeast Asia during WWII.

The retreating Japanese invaders blew up the base when the Soviet Union took Harbin in 1945.

Currently, Harbin has 27 sites related to Unit 731, 23 are included on the key relic protection list. The ruins of Unit 731 were included on China's tentative list of world cultural heritage sites in 2012.