For whatever kind of architecture, the doors do exist and present in many different ways and made of different materials.
In Chinese ancient architecute, the doors are always one of the most important element of a building. Especially for the imperial buildings, like Forbidden City in Beijing, all the doors were made in wood and painted in red and with golden locker / knocker as accessories. The color of red does not only have the meaning of happeniess and joy, but also have the willing of keeping those gosts or bad lucks away from the building. The color of gold is mainly to stand for the material of gold, which means the owner of the house is very rich and has lots of wealth. The most important factor of Chinese ancient doors are the two golden pieces in the middle, which has the function of locking the door or being a knocker. Any visitor may easily knock that part, which is made of bronze normally, and make some noise to draw attention and ask anybody to open the door for him/her.
Well, let me just show you some pictures I made as follows. Hope you may have more comments on our interesting Chinese ancient architecture. :-)