From A Wasteland,

by the side of the A1 Highway near Madrid,

to a flourishing cactus farm, all thanks to the efforts of Mercedes Garcia, an agronomist who firmly believes that low-maintenance, low-water gardens are the way of the future: the philosophy is named ‘zerolandscaping’, over 16,000 sq m of wasteland has been claimed to create Desert City, a third of which is occupied by an enclosure designed by the Madrid-based Jacobo García-Germán architecture studio, along with guided tours, research and breeding of cacti, Desert City offers a retail space, workshops, event facilities and even a restaurant,

the plot was originally a dumping ground for waste created by the construction of the highway, the project, García-Germán says, ‘has been regenerative by returning the land, at least in part, to nature, and creating a new landscape that is paradoxically natural and artificial, exotic and regressive’

and here is a quick video of the development in progress from about 1 year ago, and they even have their own blogsite, what a great use of a waste of space.