Plymouth Light, also known as Gurnet Light, is a historic lighthouse located on Gurnet Point at the entrance to Plymouth Bay in the town of Plymouth, Massachusetts. The light is accessible only by passing through the town of Duxbury, which lies to the north. The tower is located inside the earthworks of Fort Andrew, which existed in the Civil War, War o…Plymouth Light, also known as Gurnet Light, is a historic lighthouse located on Gurnet Point at the entrance to Plymouth Bay in the town of Plymouth, Massachusetts. The light is accessible only by passing through the town of Duxbury, which lies to the north. The tower is located inside the earthworks of Fort Andrew, which existed in the Civil War, War of 1812, and Revolutionary War.