It's no six-apartment combo, but even so, the latest penthouse combo listing at Philippe Starck's 15 Broad Street, aka the Downtown Insanity Palace, isn't too shabby. After about a month on the market, the apartment appears to be upping its marketing push, since a press release for the potential pad found its way into the Curbed inbox today. What's on offer are penthouses 3900 and 3910, which have "only one wall" separating them. The total ask: $7.5 million. If combined, the buyer would own half of the building's penthouse space, in the form of a 7BR, 6.5BA duplex that looks something like the floorplan above.