Born and brought up in the city, I am fascinated by anything old and rural. A recent visit to an island that has preserved its century-old way of life sparked my interest in traditional Chinese houses, front doors in particular. These doors are like a time portal, through which one travels back to a different culture, a different way of life!
The traditional Chinese houses almost always have their front doors facing south, and backdoors to the north. This has the wisdom of letting in the cooling south wind through the front doors in summer, while shutting out the freezing north wind from the backdoors in winter.
The Chinese pay much attention to symmetry and balance in everything, this is also reflected in their architecture. I can see that symmetry in doors that are opened in the middle, with hinges on both sides. Comparing to a single, bigger, heavier door, the action of pushing open two smaller doors is a much more balanced movement!
Decorating both sides of the traditional Chinese doorways are caligraphy 'duilian', blessing the occupants of the houses. These are sometimes made up and written by the heads of the families, exhibiting their wit and knowledge! These duilian, paired poetry or antithetical couplets are sophisticated and quite interesting - they are exactly matched in number and meaning of each character. Read more about it here: http://en.wikipedia.org/wiki/Duilian
Symmetrical painting of guards from heaven are sometimes pasted onto each door, to protect the occupants from evil spirits. Doors are always painted red, which stands for justice, positive energy and luck.
These decorations are usually renewed yearly before Chinese New Year.