Imagine a glorious day in your favorite city being energized at every turn. Sparkling clear air. Hardly any traffic. People alive, interesting. Appealing architecture and gardens (Figure 1.1). Amazing cultural events. Delightful diverse shopping. Food the best. Saw everything … relished it all.

Suddenly a friend appears, an ecologist. Comparing notes, she or he is equally enthusiastic. Luxuriant native street trees with lots of lichens. Clear water in the city pond. Bicycle routes and long walking routes busily used. Songbirds zipping along a shrubby tree strip between parks. No dog droppings. Wind blowing the smokestacks’ noxious air out of the city. Green walls and balconies facing each other over streets. Restaurants with rat-proof dumpsters. Elongated grass-and-flower depressions for riverside floodwaters. The intriguing list goes on. Chuckling, together you have seen almost everything, yet seemingly in two different cities.