Visionary Environment is the term given to constructions/places/spaces built by certain artists.
They are installation pieces, 'land art' compositions often containing some kind of message, but not always. Unlike sculpture or installations built by trained artists, visionary environments are built by artists without formal or academic training. Levi Strauss', "Le Bricoleur" comes close to describing these creative agents, often working with found, gathered or recycled objects, they 'make-do-and-mend', 'waste not' and re-appropriate objects in new ways often independent of their original function.
My blog on Kevin Duffy (see also Raw Vision's website) describes one such environment, located in the UK. There are many other sites throughout the world, although France and USA seem to have largest numbers....
The largest environment (to date) in terms of area and wonderment is located in India, constructed by Nek Chand. It is a 17 acre site filled with sculptures, waterfalls, follies and castles.
These artists often use concrete, which is a malleable, readily available material and quickly cast and formed into shapes. Into the concrete is set various objects, such as glass, tin cans, bangles and so on. Nek Chand has used found mud guards, bicycle frames, exhaust pipes as reinforcement onto which he adds the cement. This method of using 'ready-mades' dictated a lot of his early work. Kevin Duffy has also successfully used ready-made forms, such as buckets and traffic cones. He has even produced his own latex moulds into which he casts concrete.