This is the quintessential Chicago beach. There’s a majestic, treasured piece of architecture and a pretty beach with views of the skyline, the glittering expanse of the lake and a water crib 2.3 miles offshore. And there’s history, from its start as a suburban-style country club through racial change, threats of demolition and its famed use both in the “Blues Brothers” movie and by a young Barack and Michelle Obama for their wedding reception.