Before the advent of industrial-era construction machinery and the widespread availability of automobiles, cities were, of necessity, built to human scale. Buildings were smaller because of what it took to erect them, and cities were organized around neighborhoods, because people moved either on foot or rudimentary public transit.
Look in our cities’ older neighborhoods, to the extent they still exist, and see how livable those places can look. They were made for people, for communities.
Contrast them, for example, with the new, walled-in styrofoam-faux neighborhoods along the San Francisco Bay Area’s I-580 corridor. Every component of housing stock looks identical to every other. You must do freeway driving to get anything or anywhere. There is no feeling of place and, not coincidentally, no place where neighbors meet.
There is a place in the heart of San Francisco, down the street from the financial district, a short walk from AT&T Park, where the baseball Giants play, a nice stroll from the Embarcadero and the historic Ferry Building, adjacent to the convention center.
It is the Yerba Buena Center, a place of quiet beauty, a children’s playground, hundred year-old carousel, ice rink, bowling alley, theater, children’s museum, open space where office workers come to lunch in the fresh air.
One piece of art depicts a human standing atop the earth. Sit on a nearby chair and the human sits. Stand and the human rises. No user manual, no instructional signs. You find the secret chair by exploring. (Hint: here’s a picture.)
To the extent they are, cities are livable because they’re made to be, on purpose.
Speaking Plainly 
Agreed. Durham NC is a truly livable city thanks to 3 universities — Duke, NCU and NCCU — which makes it not only diverse, ethnically and culturallly but walkable, despite being largely built in an era when cars were king and few sidewalks were built, including in Durham. Build sidewalks!