Gate Kaiguosheng Introduction: The main gate is the core part of Huamen. It is tall and thick, majestic and solemn, and the national spirit is awe-inspiring. Three doors stand on the front, symbolizing the three ancestors of civilization, Yao, Shun and Yu. The main door in the middle is 18 meters high and is the tallest and largest door in the world. The main door is half-open, which means that the country is open and the country is prosperous in the world.