Don’t miss the Chicago Architecture Foundation’s fourth annual Open House Chicago, a free public festival that offers behind-the-scenes access to 150 buildings across Chicago. Explore repurposed mansions, hidden rooms, sacred spaces, private clubs, iconic theaters, hotels and more. Highlights include an airstream trailer on top of a roof between the Montrose and Damen Brown Line stations, a meticulously restored Frank Lloyd Wright home in Rogers Park, and a former meatpacking warehouse turned vertical urban farm.