Every inveterate walker of cities knows the allure of alleys. Dark, narrow and often damp, they tend to house trash bins, rats and worse, exposing the corroded back walls of homes or business establishments whose front entrances gleam with respectability. Alleys are as old as ancient Pompeii and Rome, where they served as servant entrances and thoroughfare for service delivery persons whose presence might upset the careful social mannerisms attendant to the front door. Alleys come alive for me every time I visit a different city and set about the walking that will help orient me to its gridlines, smells…