St. Martin Island Light

St. Martin Island Light is a unique exoskeleton lighthouse that marks one of four passages between Lake Michigan and the bay of Green Bay. Constructed in 1905, this light tower is the only example in the United States of a pure exoskeletal tower on the Great Lakes. Similar designs do exist in Canada, however.^[11] Painted white, the hexagonal tower is made of iron plates which are supported by six exterior steel posts that have latticed buttresses.^[4][12]

• http://en.wikipedia.org/wiki/St. Martin Island Light