St. John Properties, Inc. : St. John Properties, Inc. is one of the Mid Atlantic region’s largest and most successful privately held commercial real estate firms. Headquartered in Baltimore, MD, the company has developed and owns more than 17 million square feet of office, research and development/flex, retail and warehouse space. The company has over 2,000 tenants in Maryland, Colorado, Louisiana, Nevada, Pennsylvania, Utah, Virginia and Wisconsin.