Until the 1890s, New Orleans was an estuary. As land developed, it was in order of its elevation from high to low. Not until the early 1960s were the lowest-lying areas of marsh and wetlands drained to accommodate housing. This type of development, coupled with the reality of rising water levels and a sinking land base, presents a serious threat, both socially and technically, not just for New Orleans but also for coastal cities around the world where man-made defenses must withstand nature’s forces in order to preserve unstable communities on inhospitable sites. These broader environmental implications require radical solutions.