Three Men in a Boat - To Say Nothing of the Dog!
This is a somewhat fictionalized account of Jerome K. Jerome's trip down the Thames with his friends George, Harris, and Montmorency (Montmorency being the dog). As the Jerome recounts the trip, he tells stories of the past and occasionally waxes philosophical. There's even a certain amount of history related. If you like this book, you should also read Connie Willis' To Say Nothing of the Dog....