It was once the lair of Walter Bimson, the late Valley National Bank president and philanthropist whose love of money was equaled only by his love of art. And, beginning this fall, the penthouse at the top of the 77-year-old Security Building will be ground zero for Arizona State University's Phoenix Urban Research Lab (PURL), filled with busy minds looking to redesign Phoenix's core, with the interests of commerce, higher education and creative types at stake. Owned by Maricopa County, the space -- featuring exposed brick walls and tiled terraces -- will be used as offices for ASU faculty and researchers, including two representatives from the Morrison Institute, and as a hub for issues related to the design of ASU's downtown campus. From its grassy (okay, it's Astroturf, but it looks pretty) and lengthy rooftop patio, PURL visitors chatting it up with ASU prez Michael Crow can see clear past the Westward Ho all the way to Cave Creek. But, more important, they've got a great front-row seat for downtown's transformation. Below, on the eighth floor, an old ballroom has been transformed into a work and meeting space, its old wood floors buffed and painted, crumbling ceilings complemented with steel pipe and modern lighting -- a reminder of the need to preserve the old while racing toward whatever's new.