Fresh grapes sweeten the cider and turn it a beautiful amber hue. For an adult brew, stir in 1 cup rum just before serving.
Place first 7 ingredients and, if desired, anise seeds or star anise pod in a covered 4-qt. saucepan, and bring to a boil over high heat. Reduce heat to medium-low; uncover and simmer 5 minutes. Remove from heat. Mash grapes using a potato masher. Cover and let stand 15 minutes. Pour through a fine wire-mesh strainer into a heatproof pitcher; discard solids. Serve hot or cold.