The Sulphite Railroad Bridge in Franklin, New Hampshire, spans the Winnipesaukee River on a former Boston and Maine Railroad line built around 1896–97. Known locally as the Upside-Down Covered Bridge, it carried its rail bed on top of the roof, sheltering the trusses below, a rare design believed to survive nowhere else in the United States. The 234-foot bridge has three spans, including a 180-foot central span, supported by Pratt trusses on granite piers and abutments. Built to replace an 1892 trestle, it served traffic to Franklin’s paper mills until the line was abandoned in 1973 and has since stood unused.