The showing starts inside an empty office building, the kind you’d see in any humdrum workplace sitcom, stripped of its cubicles and ceiling tiles, leaving just a bare, dusty shell. Jason Thomas with Avalon Realty Advisors, a commercial real estate firm that deals with the marijuana industry’s entrepreneurs, shows off the building’s features: a fully operational HVAC system, fire sprinklers, heavy duty warehouse doors, equipped with locks. It’s a blank slate for a marijuana grower, ready to be outfitted with thousands of lights and complex water delivery systems. Legalizing marijuana in Colorado created a land rush. State law says the drug has to be grown indoors, but layers of regulation meant to curb out of state investment and tight zoning requirements have made real estate hard to come by for pot growers.