This picture is one of a series of photos from the Children's Harbor at Lake Martin, Alabama. Initially I had thought it was another lighthouse only to realize that there is a bell on the little porch area. This seems to be meant to serve the purpose of a beacon, though for what purpose I do not know.

Sizes here are (in inches): small - 10 x 7 1/2, medium - 20 x 15, large - 30 x 22 1/2.