If you’ve ever cruised down Whittier Boulevard with the windows down and the music up, or tapped your foot to an oldie that somehow always hits just right, you’ve already felt it—the Eastside Sound. Now, LA Plaza de Cultura y Artes is bringing it to the foreground with A Great Day in East L.A.: Celebrando the Eastside Sound, a new year-long exhibition opening June 28 that’s as much about music as it is about memory, movement, and cultural legacy. And yes, there’s a free concert to g...