Chesterfield, Mo. — Keystone Construction Company has completed the next phase of development at The District of St. Louis with the Hub Stl, a $4 million state-of-the-art outdoor entertainment space where families and friends gather, host events and watch sporting events, movies, live performances and more. Located in Chesterfield, Mo., at Boones Crossing, The District is a premier St. Louis-area destination for live music, food and drink as well as unique retail concepts in one walkable location. Keystone was the design/build general contractor. The developer of The District is The …