Here's an interesting talk by architect Magnus Larsson on his proposal to combat desertification by building a huge 6000km sandstone wall across Africa:
He's proposing the use of bacteria which can naturally solidify sand into sandstone in less than a day. This seems to be an intriguing new way of creating robust structures and architecture made of solid rock.
I think that India might make a better candidate to attempt something like this, perhaps in the Thar desert, between Gujarat and Rajasthan. Perhaps a large barrier could be created at the edge of the desert to prevent it from expanding, or else a large enclosure could be created in the desert, to reclaim land for agriculture. It seems like this technology could be a novel way to build interesting and rugged architecture at low cost.