After working many years in the region, the architecture, design and engineering firm HOK is opening a new studio in Denver. The firm is moving into the LoDo Towers building at 1401 17th St. The studio will officially open in the spring. “We have had people in Colorado for years,” said Bill Johnson, the design principal for the office. The firm is part of the history behind two of Colorado’s major sports venues: Coors Field and the Pespi Center, now Ball Arena.