A Day at the Diamond will be held Sat., Feb. 21 from 11am to 5pm to celebrate the grand reopening of Hohokam Stadium and the return of the Oakland A's to Mesa. The City of Mesa's free celebration gives you the opportunity to tour Hohokam Stadium and watch A's pitchers and catchers participate in their first official spring training workout at noon. The event includes a sports card show, live music, beer garden, food and a kid's zone with inflatables and games.