Almost all the buildings in the Xinyang Imperial Palace were painted red because the color red had many positive meanings such as good luck, happiness, and vitality. People who lived in the palace definitely wanted to have a good life while living in that place. Therefore, they did not use colors that would bring disaster to them.
Black was a color that was best avoided because it symbolized destruction, evil, cruelty, and sadness. Even in the Wu Li residential area, no one would use that color to paint their house, but there was a building painted with that color inside the Xinyang Imperial Palace. That building was where the Hell Prison was located.
The Hell Prison was in the southeastern area of the palace and was separated from the other buildings. Sure enough, no one wanted to go near the place where dangerous criminals were locked up, and that was why the building was surrounded by another fortress that separated it from the other buildings.