Skate parks in abandoned industrial zones, ponies grazing alongside the former Berlin Wall, flea markets in empty warehouses, music and fashion shows in hard-to-rent retail locations and climbing walls in development niches--scarcely a city in Europe has made such radically widespread use of "temporary use" projects as has Berlin in the last few decades. The idea of temporary use--which has been defined as "activity in spaces currently unsuitable or undesirable in mainstream economic cycles"--is of increasing strategic importance for urban development around the world, as individuals and...