When you want to engage people in public spaces and encourage interaction among these people, provide elements that invite people to pause for a moment.
Create objects that people can relate to so that the public place doesn't feel like just a vast open space. Make these feature that will attract people, such as water fountains or public art.
This example from Parc Andre-Citroen in Paris, illustrates this pattern on more than one level. First, this is a small garden within the much larger park, which allows people to connect with the space on a more personal level. Within the garden, a pathway of wooden blocks encourages people to slow down and experience the garden, rather than just passing through the garden.