Sustainability may conflict with other planning goals. Non-sustainable cities may be pleasanter than sustainable cities, especially for the rich and powerful. Barons generally did live better than peasants. Low density residential areas with single family villas, double garages, large gardens and heated private swimming pools do not score well on a sustainability index. Far better to have narrow streets, walk-up apartment blocks, no private cars, thick walls and small rooms, like medieval cities. One may not actually live longer, but it will certainly feel longer. The challenge for planners and designers is to create sustainable cities which are also delightful. I believe it can be done.