more than just buildings, really!
The designed environment consists of more than just buildings. Everything around us is designed in some way. Whether by nature or man, it is still designed. Here is an example of how nature shapes:
For billions of years nature has been the master shaper. Throughout that time nature has also shaped our world in various ways. Here is an example of how animals have shaped things:
In recent years humans have been shaping nature (and by recent I mean within the past 20,000 years or so). Some societies today use reciprocity and redistribution in their agriculture. What these Asian people do is clear a field of land for agricultural use and they farm it for about 10-20 years. Then they move to another nearby location and do the same thing. The reason they do this is because they don't use any chemicals when they farm, so the soil needs time to regenerate after a while of being used.
Those societies of reciprocity also represent another aspect of the designed environment - the opposition of man and nature. We need to use the land for growing foods, but only certain foods will grow there and only at certain times of the year.
But design is also more than just nature and how we interact with it. Design is also about how we interact with each other. A good example of something that's designed that allows us to interact with each other is the internet. It wasn't designed by an architect, and it wasn't invented by Al Gore either, but nonetheless it was designed. And it has revolutionized the way we interact in many ways. Take this amazingly well-written blog for example.
There are also things that are designed that affect how we interact with ourselves... Like Chinese finger traps!
All said and done, everything is designed whether by mother nature, animals, or humans. There are oppositions that we need to embrace when designing everything. All of this put together uniquely shapes the world that we all live in.