There are many Tianmen Mountains in China, one of the most well-known is located in Zhangjiajie, Human, and I've visited it during 2023 Spring Festival.
Zhangjiajie is famous for it beautiful natrual sights, and Tianmen Mountain is ranked the second from my personal opinion, it is very very large for supporting tourists to enjoy the view, and the door to the heaven(天门) is a huge one seen from the bottom.