Picture a busy avenue. Now plant trees along the boulevard, paint a mural by the empty lot, and add a community garden. Set up benches along the sidewalks and make space for kids' chalk drawings, and you've set the scene for a thriving community. Placemaking--personalizing public and semi-private spaces like front yards--is a growing trend in cities and suburbs around the world, drawing people out of their homes and into conversation with one another....