CHICAGO Last year, election night thrust Grant Park into the international spotlight. And in 2016 the Summer Olympics may call Chicago home. But between all the once-in-a-lifetime happenings, the city hosts a slew of noteworthy annual events. These are the parties, trade shows, benefits, and parades that draw media attention, tourism dollars, and top players in their fields. Here are our picks for the city’s biggest events, from Lollapalooza and the world’s largest international medical meeting to opening night at the Lyric Opera and the Arlington Million.