Mark Johnson is a rock star — at least in the world of landscape architects who rehabilitate high-profile urban riverfront properties. That world now stretches beyond Miami, Denver, and Kansas City and into our backyard. Johnson leads the urban-design crew charged with re-imagining the Los Angeles River as a beautiful, environmentally sustainable crown jewel, uniting and redefining communities across LA. Tonight, Johnson discusses the principles that guide his practice, and explains just what he's got in mind for our town.