It's been nearly 15 years since artist Jeff Koon's flowering, 43-foot-tall "Puppy" delighted visitors to Rockefeller Center. (It's now a permanent fixture at the Bilbao Guggenheim in Spain, pictured below). This summer through September 12, he's back – this time, with "Split-Rocker," a 150-ton work soaring 37 feet high and covered in 50,000 colorful summer blooms – give or take a few. Occupying the same sacred spot as Rockefeller Center's iconic Christmas tree, the immense sculpture marries stainless steel with geotextile fabric, plants, soil and an irrigation system that will keep it watered on the warmest, driest New York City summer day. The exhibit coincides with "Jeff Koons: A Retrospective" at the Whitney Museum of American Art, which opens June 27. We may be partial to the artist's work but we think both are worth a close-up look.