The 2015 B.A.A. 10K on Sunday, June 21, will bring together some of the fastest and most decorated runners in the world, led by Boston Marathon winners, World Championship medalists, and a pair of two-time B.A.A. 10K champions. Run on a blistering fast course through Boston's Back Bay and Beacon Hill neighborhood, the B.A.A. 10K will showcase several of the world's top athletes as they return to familiar territory.