The natural starting point for the work of designing cities for people is human mobility and the human senses because they provide the biological basis for activities, behavior and communication in city space. Twenty-first century urban pedestrians are the result of an evolution over millions of years. Man has evolved to move slowly and on foot, and the human body is linear in orientation. While our feet can walk or run forward with ease, they move backwards or sideways with great difficulty. Our senses have also developed to allow slow, forward movement on largely horizontal surfaces. Our eyes, ears and nose face forward to help us sense danger and opportunities on the route ahead. The rods and cones in the photoreceptor layer of the eye are organized to match our horizontal, earth-bound f ield of experience. We can see clearly ahead, peripherally to the sides, downward to some extent and much less upwards. Our arms also point forward and are well positioned for touching something or pushing branches aside along our route. In short, Homo sapiens are a linear, frontal, horizontally oriented upright mammal. Paths, streets and boulevards are all spaces for linear movement designed on the basis of the human locomotor system. One of the most memorable moments in life is the day a child stands upright and starts walking: now life is about to start in earnest. So here is our client, a pedestrian with all his attributes, potential and limitations. Basically, working with the human scale means providing good city spaces for pedestrians that take into account the possibilities and limitations dictated by the human body.