The Romance of the Three Kingdoms probably wouldn't count as a pillar of Chinese culture, but it should be at least a gargoyle. It's a novel from the 14th century attributed to Luo Guanzhong. It is a dramatic retelling of the struggles between the three kingdoms in the 2nd and 3rd century in China. There are many many Chinese movies and TV shows and other adaptations about this period of time based on this novel. Sometimes they decide to be more accurate than the novel, sometimes less accurate.
I've heard the names of various characters for years but never really knew what they did or the whole story. I've recently watched several movies based on this period of time, the most notable of which is Red Cliff, and read about the Three Kingdoms on Wikipedia. I found that the prevalence of the story in Chinese culture is kind of like the Trojan Wars and the rise and fall of Julius Caesar. Now I feel that learning about history and classic stories such as this is actually an essential part of learning the Chinese language if the primary goal is to communicate with Chinese people. These stories illustrate the Chinese thought process as well as values, which in many ways is more important to communicating than words. I wish this was a greater focus during Chinese school when I was growing up.