New London Ledge Lighthouse is a lighthouse on the Thames River in the U.S. state of Connecticut, at the mouth of New London Harbor. It was built in 1909 in the Second Empire style and was automated in 1987. In 1990, it was added to the National Register of Historic Places. The lighthouse is owned and maintained by the New London Maritime Society as part …New London Ledge Lighthouse is a lighthouse on the Thames River in the U.S. state of Connecticut, at the mouth of New London Harbor. It was built in 1909 in the Second Empire style and was automated in 1987. In 1990, it was added to the National Register of Historic Places. The lighthouse is owned and maintained by the New London Maritime Society as part of the National Historic Lighthouse Preservation Act program.