Donald Appleyard was a professor at UC Berkeley in the 1970s and 1980s. He studied the way people relate to their urban environments and how cities can be designed to improve people's lives. He did a lot of research on how the design of streets, parks, and public spaces can influence how people interact with each other, how safe they feel, and how well they know their neighbors. Appleyard showed that when cities are designed with people in mind, neighbors are more likely to look out for each other, crime rates are lower, and people feel happier and more connected to their neighborhoods.