When we lived in a big city in the 70s my mum used to let our dog out all day, thinking she went into the big park we lived next door to (I know, but people used to do that in those days) and people were always saying "I saw your dog in town the other day". Years later, when we'd moved away to another suburb, I was walking with the dog when this old lady came up and burst into tears saying "It's you! I thought you must been run over or something. My little darling!" and the dog was jumping up at her like an old friend. Apparently our dog used to traverse the city on the number 80 bus and visit adoptive friends who would feed her. Amazing really.