Many years ago, Civic Music regularly featured opera, with visits by such luminaries as the Met’s Roberta Peters and Robert Merrill, before those bookings became cost-prohibitive. We’ll honor that history at 4 p.m. Sunday, June 10, with a special “Opera at the Garden” event in partnership with Milwaukee’s Florentine Opera at the Green Bay Botanical Garden. A bonus to our five-show series and free with next year’s membership, it will be the sort of semi-informal summer concert that has been popular in other Midwest cities. More details to come.