CLAYTON, MO. — The Opus Group and AIG Global Real Estate have unveiled plans to build a six-story, mixed-use building in the downtown business district of Clayton, a western St. Louis suburb. The project will feature five stories of residential units. The units will be a mix of studio, alcove, one- and two-bedroom apartments. The ground level will consist of 13,000 square feet of retail space. Amenities will include a Fitness On Demand studio, secure bike storage, a rooftop terrace, clubroom, game room and a fire pit/grill area. Opus Development Company LLC will be the developer, and Opus Design Build LLC will be the design-builder. Opus AE Group LLC will be the engineer and project architect. Construction will begin late this year, and completion is slated for March 2017.