Chinese doors almost always bear decoration of some type.
The dui lian are the set of banners hung above and to the sides of the door. They are always red and have a message of good luck or blessings of prosperity.
On the doors themselves you will find one of two things – either a door god as seen above or a single Chinese character fu as you can see on the door below.
One fascinating feature of the fu on the door is that it is always placed upside down. Why? This is a bit of a pun. The word for “upside down” sounds the same as the word that means “to arrive.” So they take the blessing and turn it upside down to mean “blessings arrive.” It’s a way of inviting blessings to the home.
Any door or gate can be decorated in this way. Below is a pig stall with dui lian to protect the pigs living inside.
You can even buy your own (pricey) dui lian online at a Chinese Wedding retailer. (What is NOT on the Internet?)
Although all the pictures I’ve included here come from more old-fashioned rural dwellings, modern apartments also have the same door decorations. I could include pictures from my own building neighbors, but they certainly don’t look as interesting as these above. 
Most of them do have the dui lian and the fu.
