I had a version of this at North Italia in Irvine. This refreshing recipe is perfect for a hot summer day, makes a pitcher of Rosemary & Lime and is quite potent. Use 3/4 soda to 1/4 mixture if you don't want the party to end early.
750 ml Gin
10 oz Lime Juice
12.5 oz Rosemary Simple Syrup
Combine the gin, lime, and syrup in a large pitcher and mix. Add some lime wheels and rosemary sprigs if you want it to look attractive. Fill a glass with crushed ice, fill the glass 1/4 of the way with the mixture, top off with soda, and garnish with mint. For added flavor add 1-3 dashes of bitters and/or 1/4 oz of Amaro.