Harry Brignull, a User Experience Consultant, recently mentioned this on the Anthrodesign email list:

http://www.youtube.com/watch?v=S2GfOhFZkY8

This is one of the great works of empirical sociology: using a time lapse camera (and an analog clock) to study the flow of people over time through several spaces in New York City in the 1970s.

The associated books, City: Rediscovering the Center and the Social Life of Small Urban Spaces are masterpieces in the study of social interaction in specific locations.

The larger related work, City, ranges more widely to include sidewalks and the struggle between pedestrians seeking seating and property owners who want them to roost elsewhere.