The billowing stainless steel forms of Frank Gehry’s Pritzker bandshell seem to float up from behind the 3.5-acre Lurie Garden in Millennium Park, backed by Chicago’s celebrated skyline. Another landmark in a city long a laboratory for innovation in architecture and landscaping, the garden has been called a “model of responsible horticulture.” Masses of flowering perennials and grasses are a striking counterpoint to the surrounding walls of concrete and glass. Perhaps most unexpected, at a place that sits atop a 4,000-vehicle underground parking garage and railroad depot in the inner city, are the bees that flit from flower to flower.