Billionaire businessman William Koch just listed his 32,614-square-foot Aspen mansion for $89.9M. Not only is it Aspen's most expensive listing by a landslide—a hair under double the cost of the moneyed Colorado city's second most expensive listing ever—it's also No. 13 on the country's list of priciest houses on the market right now, behind just five NYC highrise mansions, two L.A. properties, one Hamptons manor, one San Francisco estate, one Texas manse, and one boring private island in Florida. What does one get these days for $90M in Colorado? A 15-bedroom mainhouse, for one, plus nine other buildings on its 55 acres. Compared to NYC it seems like a deal, though it's worth considering that Koch bought the property in 2007 for just $26.5M.