Bring all ingredients to a boil in a medium saucepan, stirring until sugar is dissolved. Let stand at room temperature, covered, 1 hour, then transfer to an airtight container and chill until cold, about 1 hour. Strain syrup thourough a sieve into a bowl, pressing hard on and then discarding solids.  To make basil lemonade, combine 2 cups syrup with 2 cups cold water, 2 cups ice, and 1 ¼ cups fresh lemon juice.  The syrup can also be used to flavor cocktails- like a lemon basil gimlet!