The Grand Lake St. Marys Lighthouse, also known as the "Northwoods Lighthouse", is a historic lighthouse on Grand Lake St. Marys, a reservoir in the far western part of the U.S. state of Ohio. Located east of the city of Celina in Mercer County, the lighthouse was built in 1923, using a plan modelled after the Eddystone Lighthouse off the coast of Cornwall in the United Kingdom.A predominately concrete structure, the lighthouse rests on a stone foundation. Measuring from foundation to pinnacle, it is covered with a dome of bronze and glass that surrounds the beacon; the dome is crowned with a decorative weathervane.Although the lighthouse was built partially for ornamental purposes, it has also served as an active lighthouse. In its earliest years, it operated in a standard lighthouse role between April and November under a license from the U.S. Coast Guard. Grand Lake St. Marys was built to provide water for the Miami and Erie Canal; although the canal had ceased operations by 1923, there was still sufficient lake traffic to warrant the use of a lighthouse on this peninsula, which protrudes into the northern shore of the lake. Today, it is one of three lighthouses on Grand Lake St. Marys: the Celina Rotary Club erected an operating lighthouse in 1986, at the lake's northwestern corner, and a third lighthouse was completed on the lake's southern shore in 2003. Unlike the other two lighthouses, the Northwoods Lighthouse is not easily accessible by land.
