A twenty-meter-tall square chimney rises from an empty lot in Qiqihar’s Tiefeng District. It resembles an ordinary relic of early twentieth-century industry. A rusted boiler room and the crumbling first floor of an L-shaped brick building—measuring thirty meters long and six meters wide—sit beside it. This decaying perimeter contains the headquarters of the Kwantung Army’s Unit 516, the command center for Japan’s chemical warfare operations during World War II. The architecture demonstrates a calculated act of erasure. In August 1945, fleeing Japanese forces detonated the main one-thousand-square-meter testing facility to conceal their atrocities.

Within these surviving foundations, military chemists engineered mass death. Between 1939 and 1945, 250 technical specialists developed mustard gas, lewisite, and phosgene. They utilized an on-site bottle-making workshop and extensive underground networks to manufacture and store their munitions. A narrow subterranean entrance, measuring just one meter by eighty centimeters, drops into the dark earth. Above ground, officers forced Chinese, Soviet, and Mongolian prisoners into sealed glass observation chambers. Scientists stood outside with stopwatches, recording the exact moments human subjects succumbed to the blistering and choking agents. They calibrated the lethality of artillery shells marked with color-coded rings—yellow for skin-blistering mustard gas, red for incapacitating sneezing agents, and green for tear gas.

After the war, the ruins housed a civilian glass factory and local residents. These occupants lived directly above a heavily contaminated environment. The most dangerous elements of Unit 516 remain buried out of sight. Defeated soldiers buried countless chemical shells in the surrounding dirt and dumped them into the nearby Nen River. The landscape itself became a delayed-action weapon. In 2003, construction workers unearthed five rusting barrels in Qiqihar. The resulting mustard gas leak killed one person and permanently disabled forty-three others. The soil holds its poison tightly.

Today, a heavy metal fence surrounds the site, keeping the public at a safe distance from the unexploded ordnance. The strict prohibition of entry acts as a physical extension of the site's history. The danger remains entirely active. The crumbling chimney and the sealed tunnels stand as fixtures of an unfinished war, demanding recognition that the violence of 1945 continues to poison the ground of the present.