Every Tuesday, Wednesday and Thursday the first couple of months this summer, catch free events in the Flatiron District. The series kicks off with a summer solstice celebration at the National Museum of Mathematics (June 20). After that, Tuesdays will be devoted to tech and business classes, Wednesdays will bring free fitness classes and “Throwback Thursdays” mean board games, cornhole and other fun diversions. The events will take place on the North and South Plazas of Madison Square Park. For more information, visit flatirondistrict.nyc.