OPO Startups is a place where entrepreneurs, remote workers & small businesses can hFounded in 2015 by Randy Schilling, OPO Startups transformed the landmark 1909 Old Post Office building on Historic Main Street into one of Missouri's most unique coworking campuses. What started as a single building has grown into an 8-building, 50,000+ sq ft innovation community spanning a full city block. From $20 drop-in day passes to fully furnished private office suites, OPO offers the infrastructure, community, and historic address that entrepreneurs and businesses in St. Charles County need to thrive.ave meetings, work & collaborate!